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Jarvis 
Investigation  on  jigging 


INVESTIGATION  ON  JIGGING. 


BY 

ROYAL  PRESTON  JARVIS,  E.M.,  A.M., 

3rofessor  of  Mining  and  Metallurgy  in  the  University  of  Tennessee, 
KNOXVILLE,  TENN. 


STRMITTED  IN  PART  FULFILLMENT  OP  THE  REQUIREMENTS  FOR  THE 

DEGREE  OF  DOCTOR  OF  PHILOSOPHY,  IN  THE  FACULTY 

or  PURE  SCIENCE,  COLUMBIA  UNIVERSITY, 

MARCH,  1908. 


NEW     YORK,    N\    Y. 

1908. 


BIOGRAPHICAL  SKETCH. 

ROYAL  PRESTON  JARVIS  was  born  in  Riverton,  Iowa,  Feb.  ~J8, 
875.  In  the  spring  of  1880  he  moved  with  his  parents  to  the 
otate  of  Colorado,  and  continued  to  reside  in  that  State  until 
1 900,  with  the  exception  of  a  few  brief  visits  East;.  His  early 
education  was  obtained  in  the  schools  of  Crested  Butte,  Colo., 
graduating  from  the  Gunnison  High  School  in  18f93.  In  the. 
fall  of  this  year  he  matriculated  at  the  Colorado  School  of 
Mines,  graduating  therefrom  with  his  class  in  18157.  Later  'he 
accepted  the  position  of  assayer  in  the  works  of  the  Bimetalli' 
Smelting  Co.,  of  Leadville,  Colo.,  and  remained  m  the  employ 
of  this  company  until  the  plant  was  permanently  clu  ed  in  19'" 


In  the  fall  of  1900  he  entered  Columbia  Universit 
student,  and  attended  most  of  the  session  of  1900- 


fall  of  1901  he  was  appointed  chemist  to  the  Cia. 


a  grarlu 
31.     In  the 


tfetalurgica 


de  Torreon,  Torreon,  Mexico.  He  remained  with  tlais  company 
until  the  spring  of  1903,  finally  filling  the  positioi/of  Assistant 
Superintendent  of  the  plant.  Mr.  Jarvis  was  appointed  to  the- 
chair  of  Mining  and  Metallurgy  in  the  Washington  State  Col- 
lege in  the  fall  of  1903,  which  position  he  occupied  for  three 
years.  In  the  fall  of  1906  he  resumed  his  work)  in  Columbia 
University,  and  received  the  degree  of  A.M.  in  1907.  He 
was  appointed  in  the  spring  of  1907  to  fill  the  'iewly-created 
chair  of  Mining  and  Metallurgy  in  the  University  of  Tenne 
at  Knoxville. 


SUBJECT  TO   REVISION. 

: —  7  /V 

[TRANSACTIONS  OF  THE  AMERICAN  INSTITUTE  OF  MINING  ENGINEERS.] 


Investigation  on  Jigging.* 

BY  ROYAL  PRESTON  JARVIS,  E.M.,  A.M.,f  KNOXVILLE,  TENN. 

(Chattanooga  Meeting,  October,  1908.) 

TABLE  OF  CONTENTS. 

PAGE 

I.  INTRODUCTION, 1 

II.  REVIEW  OF  PREVIOUS  INVESTIGATIONS, 2 

III.  RESUME  OF  RESULTS  OF  PREVIOUS  PRELIMINARY  WORK,         .        .        4 

1.  Hydraulic-Classification  Tests, 5 

2.  Pulsion-Jig  Tests, 5 

3.  Vezin  Laboratory-Jig  Tests, 7 

A.  Suction, 8 

B.  Feed-Water  and  Rate  of  Feed, 9 

C.  Filter-Bed, 9 

D.  Length  and  Number  of  Strokes, 9 

E.  Concentration, 9 

F.  Specific  Gravity, 9 

4.  Five-Sieve  Harz-Jig  Tests, 9 

IV.  TESTS  WITH  THE  JARVIS  LABORATORY-JIGS 11 

1.  Construction,      ...........       12 

2.  Materials  and  Other  Accessories, 17 

A.  Screens, 17 

B.  Sieve-Sizes, 18 

C.  Bedding, 18 

D.  Minerals, 18 

E.  Specific  Gravities, 18 

F.  Feed, 19 

3.  Method  of  Conducting  the  Tests, 20 

4.  Record  of  Results, 22 

5.  Discussion  of  Results,        . 45 

V.    DISCUSSION   OF   PULSION   AND  SUCTION, 59 

VI.  DISCUSSION  OF  ACCELERATION, 62 

VII.  RESUME  AND  CONCLUSIONS, 63 

I.  INTRODUCTION. 

The  jig,  in  one  form  or  another,  continues  to  hold  a  leading 
place  among  the  machines  designed  to  separate  two  or  more 

*  Submitted  in  part  fulfillment  of  the  requirements  for  the  degree  of  Doctor  of 
Philosophy  to  the  Faculty  of  Pure  Science,  Columbia  University,  and  accepted 
for  publication  in  the  Transactions  of  the  American  Institute  of  Mining  Engineers. 

f  Professor  of  Mining  and  Metallurgy  at  the  University  of  Tennessee,  Knox- 
ville,  Tenn. 


2  INVESTIGATION    ON    JIGGING. 

minerals  of  different  specific  gravities.  It  is  simple  in  construc- 
tion, easily  operated,  capable  of  treating  large  quantities  in  a 
short  time,  and  highly  efficient  under  various  conditions. 

The  question,  whether  the  material  to  be  jigged  has  first  been 
sized,  determines  the  two  principal  methods  of  jigging.  Jigging 
preceded  by  close  sizing,  generally  known  as  the  Continental  or 
German  system,  involves  a  more  or  less  elaborate  series  of 
screens  or  trommels,  with  attendant  cost  for  installation,  opera- 
tion, and  repairs.  Jigging  without  sizing,  known  as  the  English 
system,  is,  according  to  Munroe,1  "  a  development  of  the  hand- 
jigging  formerly  employed  in  Cornwall  .  .  .  and  introduced 
by  English  miners  to  this  country."  In  its  simplest  form, 
the  method  consists  in  jigging  an  ore-mixture  previously  crushed 
to  some  maximum  size  (although,  in  some  cases,  even  this  pre- 
liminary is  omitted)  on  a  relatively  coarse  sieve,  and  then  jig- 
ging again  on  a  finer  sieve,  the  material  passing  through  the 
first  sieve  and  bedding.  While  many  modifications  have  been 
necessary  to  adapt  it  for  use  in  mills  of  large  capacity,  where 
hand-work  was  necessarily  replaced  by  machines,  the  principle 
remains  the  same;  the  fact  that  the  English  system  has  been 
successfully  employed,  both  in  this  country  and  abroad,  is  well 
known;  and  arguments  have  been  made  for  its  efficiency  and 
applicability  in  a  wider  sphere  than  it  has  occupied  hitherto. 

II.  REVIEW  OF  PREVIOUS  INVESTIGATIONS. 

The  fact  that  treating  a  mixture  of  minerals  under  jigging 
conditions  increased  the  amount  of  mineral  saved;  or,  as  Pro- 
fessor Richards  aptly  terms  it,  "  the  extra  jig-catch,"  has  long 
been  known.  To  account  for  this  fact  a  number  of  theories 
have  been  proposed.  The  work  of  Rittinger2  in  this  field  has, 
for  many  years,  been  a  classic  in  the  literature  of  ore-dressing. 
For  the  purposes  of  my  present  paper,  however,  the  work  of 
two  American  investigators,  Prof.  H.  S.  Munroe  and  Prof.  R.  H. 
Richards,  is  chiefly  concerned. 

Professor  Munroe  has  given  the  results  of  an  elaborate  series 
of  experiments,3  and  his  deductions,  based  largely  on  theoretical 
grounds,  of  this  work.  After  reviewing  briefly  the  two  systems 
of  jigging,  followed  by  a  discussion  of  Rittinger's  formulas  and 

1  Trans.,  xvii.,  637  (1888-9).  3  Aufbereitungskunde,  pp.  165,  270. 

3  Trans.,  xvii.,  657  (1888-9). 


INVESTIGATION    ON    JIGGING. 

the  derivation  of  them,  and  after  a  careful  study  of  the  behavior 
of  grains  (usually  shot)  in  a  tube  en  masse,  acted  upon  by  a  rising 
current  of  water,  he  is  led  to  conclude  that  the  interstitial  cur- 
rents play  a  very  important  role,  and  are  responsible  for  the 
high  ratios  of  concentration  obtainable  in  the  English  system 
of  jigging.  Since  his  conclusions  bear  directly  upon  the  present 
investigation,  they  are  given  in  full,  as  follows : 

' '  1.  Bodies  falling  through  water  in  a  tube  do  not  attain  as  high  a  velocity  as  in 
falling  through  the  same  medium  in  large  vessels. 

"  2.  The  falling  velocity  is  but  little  affected  when  the  diameter  of  the  body  is 
less  than  one-tenth  that  of  the  tube. 

"3.  The  falling  velocity  is  the  more  retarded  as  the  diameter  of  the  body 
approximates  that  of  the  tube. 

"4.  A  sphere  four-tenths  the  size  of  the  tube  will  develop  the  greatest  falling 
velocity,  and  will  require  a  current  of  maximum  velocity  to  support  or  raise  it. 

"5.  Grains  falling  en  masse  are  really  moving  in  confined  channels,  and  follow 
the  law  of  the  movement  of  bodies  in  tubes.  The  falling  velocity,  and  the  velocity 
of  the  current  necessary  to  support  or  raise  a  mass  of  grains,  increase  and  dim- 
inish with  the  distance  apart  of  the  grains. 

"6.  The  diameter  of  the  channel  in  which  the  single  grain  moves  equals  the 
cube  root  of  the  volume  of  the  grain  with  its  proportion  of  the  interstitial 
space.  .  . 

"7.  In  a  mass  of  grains  of  different  sizes,  the  large  grains  move  relatively  in 
smaller  channels  than  the  small  grains.  The  ratio  of  the  diameters  of  equal-fall- 
ing grains  of  quartz  and  galena,  under  such  conditions,  is  31  to  1,  instead  of  4  to 
1 ,  which  latter  ratio  holds  good  for  free-falling  grains  only. 

"8.  The  formulae  for  grains  moving  in  tubes,  when  applied  as  above  to  grains 
moving  en  masse,  enable  us  to  compute  the  velocity  of  jig-currents  and  thus  deter- 
mine the  proper  length  and  number  of  strokes  of  the  jig-piston.  The  old  formulae 
gave  results  many  times  too  large. 

"9.  The  present  investigation  demonstrates  that  close  sizing  is  not  necessary  for  the 
separation  of  different  minerals  by  jigging,  unless  the  difference  in  specific  gravity  is 
small.  .  .  . 

"  10.  Downward  currents  are  apparently  necessary  to  success  in  jigging  through 
a  bed.  This  requires  confirmation  by  experiments  on  a  larger  scale. 

"11.  Very  fine  material,  less  than  y1^  millimeter  in  diameter,  can  be  treated  suc- 
cessfully on  jigs,  if  treated  with  coarse  stuff,  the  concentration  taking  place  in  the 
small  interstitial  channels  between  the  grains  forming  the  mineral  bed.  For  the 
treatment  of  fine  stuff  on  jigs,  dose  sizing  is  a  positive  disadvantage.  Jigs  work  well  on 
mixed  stuff,  and  very  badly  on  fine  stuff  alone.  Stuff  less  than  four-tenths  the 
size  of  the  smallest  interstitial  channels  cannot  be  treated  successfully  in  this  way. 

"12  The  size  of  the  mesh  of  the  jig-sieve  has  a  very  important  influence,  and 
must  be  proportioned  to  the  work  to  be  done. 

"13.  The  English  method  of  jigging  without  sizing,  except  possibly  so  far  as 
is  necessary  to  remove  the  very  finest  slimes,  has  many  advantages,  and  should  be 
more  generally  adopted." 

Professor  Richards,4  in  a  very  careful  and  elaborate  investiga- 


Trans.,  xxiv.,  p.  409  (1894). 


4  INVESTIGATION    ON    JIGGING. 

tion  on  the  question  of  jigging  relatively  small  sizes,  treats  it 
under  four  heads:  (1)  the  law  of  equal-settling  particles;  (2) 
the  law  of  interstitial  currents ;  (3)  the  law  of  acceleration ; 
and  (4)  the  law  of  suction.  These  four  laws  are  supposed  to 
govern  all  jigging  operations.  Practically,  Professor  Richards's 
full  conclusions  are  : 5 

"The  two  chief  reactions  of  jigging  are  pulsion  and  suction. 

"The  effect  of  pulsion  depends  upon  the  laws  of  equal-settling  particles,  inter- 
stitial currents,  and,  possibly,  also  of  acceleration.  The  chief  function  of  pulsion 
is  to  save  the  larger  grains  of  the  heavier  mineral,  or  the  grains  which  settle 
faster  and  farther  than  the  waste. 

' '  The  effect  of  suction  depends  upon  the  interstitial  factor  of  the  minerals  to  be 
separated.  ...  If  this  factor  is  greater  than  3.70,  suction  will  be  efficient  and 
rapid.  If  the  factor  is  less  than  3.70,  suction  will  be  much  hampered  and 
hindered.  The  use  of  a  long  stroke  will  help  to  overcome  this  difficulty.  The 
chief  function  of  suction  is  to  save  the  particles  that  are  too  small  to  be  saved  by 
the  laws  of  equal-settling  particles,  and  of  interstitial  currents,  acting  through  the 
pulsion  of  the  jig. 

"  For  jigging  mixed  sizes,  pulsion  with  full  suction  should  be  used. 

' '  For  jigging  closely-sized  products,  pulsion  with  a  minimum  of  suction  should 
be  used." 

He  concludes  by  saying,  in  effect : 

In  jigging  minerals  having  an  interstitial  factor  greater  than  3.7,  sizing  is  sim- 
ply a  matter  of  convenience,  although  the  fine  sizes  should  be  removed  in  some 
suitable  manner.  But  if  the  factor  is  less  than  3.7,  then  the  jigging  of  mixed  sizes 
cannot  give  a  perfect  separation,  and  if  this  is  desired,  then  close  sizing  must  be 
adopted,  and  the  closer  the  sizing  the  more  perfect  the  jigging.  As  an  expedient, 
however,  there  are  often  cases  where  a  satisfactory  separation  may  be  attained 
without  sizing. 

The  differences  in  the  conclusions  of  the  two  investigators 
above  quoted  have  been  chiefly  influential  in  suggesting  this 
present  investigation,  which  was  begun  in  the  fall  of  1906,  and 
the  results  of  the  work  done  in  the  Mining  Laboratory  of  the 
Columbia  School  of  Mines  have  been  embodied  in  a  paper 
submitted  to  the  Faculty  of  Pure  Science  in  Columbia  Univer- 
sity. Since  most  of  the  work  done  then  was  preliminary  to 
that  recently  undertaken,  I  include  herewith  a  resum&  of  my 
former  results  and  conclusions. 

III.  RESUME  OF  THE  RESULTS  OF  PREVIOUS  PRELIMINARY 

WORK. 

In  the  following  investigation  an  effort  was  made  to  deter- 
mine, among  other  things:  (1)  the  conditions  and  laws  of 

5  Trans.,  xxiv.,  485  (1894). 


INVESTIGATION    ON    JIGGING.  5 

hydraulic  classification ;  (2)  the  conditions  and  limitations  of 
iigging  in  the  pulsion-jig;  (3)  the  effect  of  varying  the  length 
and  number  of  strokes  per  minute  in  the  Vezin  laboratory-jigs; 
(4)  experiments  with  a  large  5-compartment  Harz  jig  to  deter- 
mine the  limits  and  perfection  of  separation  effected  in  an  ore 
containing  galena  and  sphalerite  with  a  quartzose  gangue. 

Considered  briefly,  the  results  of  these  tests,  in  the  above- 
named  order,  are : 

1.  Hydraulic  Classification. 

A  number  of  tests  were  made  with  quartz  paired  with 
galena,  antimony,  arsenopyrite,  magnetite,  sphalerite,  etc.,  in 
different  proportions,  and  with  a  velocity  varied  between  wide 
limits,  in  order  to  determine  whether  a  fixed  ratio  existed  as  to 
the  diameters  of  the  grains  of  the  two  minerals.  All  tests  under 
this  head  were  made  in  a  Munroe  hydraulic  laboratory-classi- 
fier. Without  going  into  details  of  the  methods,  etc.,  the  re- 
sults indicated  that  whether  or  not  a  more  perfect  separation 
was  effected  in  the  classifier-tube  itself,  the  manner  of  drawing 
off  the  classified  products  always  resulted  in  giving  a  large 
proportion  of  mixed  products,  and  after  a  number  of  calcula- 
tions upon  different  drawings,  similar  to  the  manner  detailed 
under  the  pulsion-jig  tests,  and  described  by  Professor  Rich- 
ards,6 proved  to  my  satisfaction  that  no  such  ratio  existed  with 
classified  products  under  the  conditions  the  above  type  of  clas- 
sifier was  operated  and  the  products  removed. 

2.  Pulsion-Jig    Tests. 

The  largest  size  of  Munroe  hydraulic  classifier  was  first 
fitted  up  in  such  way  that  a  column  of  ore  5  to  6  in.  long  was 
supported  upon  a  bedding  of  large  grains,  and  then  treated 
with  a  pulsating  current  of  water.  The  tube  in  which  the 
jigging  took  place  had  a  diameter  of  about  1.75  in.,  and  the 
pulsion  was  effected  by  compressing  a  rubber  tube  connecting 
the  bottom  of  the  ore-column  with  a  pressure-head  of  water. 
The  compression  of  the  tube  was  effected  both  by  mechanical 
means  and  by  hand,  and  apparently  it  made  little  difference 
which  method  was  used.  The  bedding-grains  served  only  to 
support  the  ore-column  and  confine  it  within  the  tube ;  and  in 

6   Op.  tit.,  p.  450,  et  seq. 


6  INVESTIGATION    ON    JIGGING. 

drawing  off  the  products  this  was  always  first  to  be  removed. 
The  results  of  jigging  under  these  conditions  and  the  removal 
of  the  jigged  product — namely,  by  allowing  the  jigged  material 
to  subside  gradually  into  a  rubber  tube  connected  with  the  re- 
ceptacle which  supported  the  bedding,  if  it  may  be  called  such, 
and  which  was  really  the  hutch  of  the  jig,  were  that  after  dry- 
ing, screening,  weighing,  and  analyzing  the  different  screen- 
products  from  a  number  of  drawings,  and  finally  calculating 
the  ratios  between  the  diameter  of  the  grain  of  quartz  and 
that  of  the  other  mineral  paired  with  it,  no  such  ratio  as  that 
given  by  Richards  could  be  obtained  under  such  conditions, 
but  the  tests  were  in  all  respects  duplicates  of  the  first  series 
run  with  the  classifier  operated  under  the  conditions  of  hydraulic 
classification. 

It  was  found,  however,  that  if  the  jigged  products  were  not 
removed  from  the  jigging-tube  as  above  described,  but,  instead, 
a  screen  attached  to  the  lower  end  of  the  jigging-tube,  and  the 
mixture  of  minerals  jigged  on  this  screen,  and  then  instead  of 
drawing  off  the  products  through  the  rubber  tube  at  the  bot- 
tom the  entire  apparatus  was  dismantled,  and  the  jigged  prod- 
ucts removed  from  the  tube  by  inserting  a  piston  and  forcing 
the  ore-column  from  the  bottom  of  the  tube,  cutting  sections 
at  equal  intervals,  that  approximate  concordant  results  were 
obtained.  These  sections,  which  were  cut  off  at  equal  intervals, 
and  usually  eight  or  nine  in  number,  were  dried,  sized  on  a  nest 
of  sieves,  weighed,  and  analyzed.  Ratios  of  diameters  were 
then  calculated  for  some  four  or  five  drawings,  in  which  the 
mixed  grains  occurred,  according  to  the  method  described  by 
Richards,7  which  was  as  follows :  The  average  diameter  of  the 
quartz-grains  was  obtained  by  multiplying  all  the  quartz-weights 
in  a  particular  drawing  by  their  diameters,  and  dividing  the  sum 
of  the  products  by  the  sum  of  their  weights ;  and  similarly  for 
the  other  mineral  paired  with  it.  The  average  diameter  of  the 
quartz-grain  thus  determined  is  divided  by  the  average  diame- 
ter of  the  grains  of  the  other  mineral,  and  the  quotient  is 
the  desired  ratio.  Table  I.  gives  the  ratios  that  were  obtained 
with  the  pulsion-jig,  the  material  in  nearly  all  cases  being  sized 
between  0.15  and  2  mm.  For  purposes  of  comparison  I  have 
included  the  ratios  obtained  by  Professor  Richards8  with  a 

7  Trans.,  xxiv.,  450  (1894.  •  Trans.,  xviv.,  463  (1894). 


INVESTIGATION    ON    JIGGING. 


pointed  tube,  the  results  of  which  he  considers  to  hold  true  for 
the  pulsion-jig  as  well. 

TABLE  I. — Equal-Settling  Ratios  of  Minerals  in  Pulsion-Jigs. 


Name  and  Specific  Gravity. 

Ratio  for 
Pulsion-Jig. 

Richards's  Ratio. 

Quartz, 

f  Galena,  7.14  
i  Antimony,  6.66  
Arsenopyrite,  5.71  
Magnetite,  4.76  
Sphalerite  3  70  

5.80 
5.20 
4.42 
3.65 
2.61 

5.842 
4.896 
3.737 
not  given. 
2.127 

In  the  tests  of  Table  L,  50  per  cent,  by  volume  of  each  min- 
eral was  used.  It  seems  evident,  therefore,  that  under  the  con- 
ditions that  exist  under  the  influence  of  pulsion  alone,  the  free- 
settling  ratios  obtained  with  Rittinger's  formula9  are  increased, 
but  by  no  great  amount. 

3.    Vezin  Laboratory-Jig  Tests. 

Without  going  into  the  details  of  construction  of  this  very 
useful  little  laboratory-apparatus,  suffice  it  to  say  that  the  piston 
is  driven  by  a  variable-speed  shaft,  with  a  disk  and  friction- 
wheel,  and  the  number  of  strokes  may  be  varied  from  100  to 
300  per  min.,  and,  with  a  double  eccentric,  the  length  of  stroke 
from  0  to  1.25  in.  (31.7  mm.).  The  box  carrying  the  sieve  is 
attached  to  the  body  of  the  jig  by  means  of  clamps,  so  that, 
together  with  the  ore  and  bedding  resting  on  the  sieve,  it  may 
easily  be  removed  and  the  contents  examined,  or  another  box 
with  its  attached  sieve  substituted.  In  all  tests  with  the  Vezin 
jig  a  sieve  of  8-mesh  (2.2  mm.  square  hole)  was  used.  The 
bedding  was  in  most  cases  sized  between  the  limits  of  2.5  and 
3.3  mm.,  and  maintained  at  a  thickness  of  0.75  in.  (19  mm.). 
The  jig  was  driven  from  a  counter-shaft  by  an  electric  motor, 
so  that  a  uniform  speed  was  secured.  The  feed  in  all  cases  was 
sized  between  the  limits  of  0.10  and  1.9  mm.,  and  the  various 
mixtures  were  made  up  by  volume  to  contain  3  of  quartz  and 
1  of  the  heavier  mineral.  From  1.6  to  2.0  kg.  represented  the 
amount  generally  employed  in  each  test.  After  this  quantity 
had  been  run  over  the  jig  it  was  stopped,  the  sieve-box  removed, 
the  contents  placed  in  a  large  pan  and  dried,  the  hutch-work 

9  Trans.,  xvii.,  639  (1888-9;  ibid.,  zxiv.,  411  (1894). 


8  INVESTIGATION    ON    JIGGING. 

drawn  off,  the  water  decanted  and  treated  in  the  same  way,  and 
finally  the  tailings  were  freed  as  far  as  possible  from  water  and 
dried.  The  three  products  were  then  sized  separately  on  a  nest 
of  sieves,  each  size  weighed  and  analyzed,  the  material  being 
subsequently  used  again  for  another  test. 

It  is  evident  that  in  so  simple  a  machine  as  the  Vezin  jig 
there  are  a  number  of  factors  that  may  be  made  either  constant 
or  variable.  Thus  the  length  of  stroke  and  number  per  min. 
are  easily  varied,  or  may  be  kept  constant;  the  size  of  the 
grains  constituting  the  bed,  and  its  thickness,  may  be  varied 
within  limits,  although  this  is  likely  to  vary  with  other  factors, 
especially  the  piston-speed ;  then  the  quantities  of  water  used 
on  the  piston  side,  with  the  feed  and  the  amount  discharged 
from  the  hutch,  as  well  as  the  rate  of  feed,  may  also  be  varied. 
In  these  tests  the  length  and  number  of  strokes  were  the  prin- 
cipal variables,  and  also  the  amount  of  suction,  of  which  there 
are  a  number  of  degrees,  limited  as  follows  : 

(A)  Full  suction.     In  which  the  hutch-spigot  is  fully  open, 
and  the  water  thus  discharged  is  supplied  entirely  by  increasing 
the  amount  added  with  the  feed,  and,  if  possible,  cutting  down 
the  amount  supplied  to  the  piston  side. 

(B)  Part  suction.    In  which  the  hutch-spigot  is  not  fully  open, 
and  does  not  discharge  a  quantity  equal  to  the  extra  amount 
added  with  the  feed. 

(C)  Balanced  suction.     In  balanced  suction  the  hutch-spigot 
is  closed  and  the  feed-water  and  piston-water  are  equal ;  or  the 
hutch-spigot  is  partly  or  fully  open,  and  the  amount  thus  dis- 
charged is  supplied  entirely  from  the  piston  side. 

The  results  obtained  indicate  the  following  conclusions : 
A.  Suction. — With  full  suction,  (A),  the  bed  was  not  mobile, 
and  after  a  few  minutes'  feeding  the  jig  was  very  badly  choked 
and  little  or  nothing  passed  into  the  hutch.  After  trying  a  few 
tests  with  the  same  bad  results,  full  suction  was  considered 
impracticable.  In  the  case  of  part  suction,  (B),  the  mobility 
of  the  bed  was  decreased  in  proportion  to  the  amount  of  suc- 
tion, and  with  it  a  decrease  in  the  amount  of  coarse  mineral 
passing  into  the  hutch,  but  with  a  corresponding  increase  in 
the  amount  of  fine  material  without  a  noticeable  enrichment. 
The  best  results  were  obtained  with  balanced  suction,  having 
the  spigot  completely  closed,  although  the  results  with  the 


INVESTIGATION    ON   JIGGING.  9 

spigot  partly  or  fully  open  did  not  differ  materially  from  those 
of  full  suction  (A). 

B.  Feed-  Water  and  Rate  of  Feed. — These  factors  were  kept  as 
nearly  constant  as  possible,  and  the  effect  of  varying  them  was 
not  considered. 

C.  Filter-Bed. — The  thickness  and  the  size  of  the  filter-bed, 
also,  were  made  a  constant.     It  was  found,  however,  that  the 
shape  of  the  grains  of  the  bedding  does  influence  the  ease  and 
rapidity  with  which  the  mineral  passes  into  the  hutch.     Thus 
with  antimony  and  arsenopyrite,  both  of  which  break  into  long, 
pencil-shaped  grains,  the  sieve  became  quickly  blinded,  which 
interfered  with  the  free  passage  of  grains  below,  and  required 
a  long,  heavy  stroke  to  dislodge  them. 

D.  Length  and  Number  of  Strokes. — The  results  of  the  tests 
seemed  to  show  that  the  character  of  the  separation  is  not 
directly  dependent  upon    absolute  piston-speed,  but  that  the 
quick,  short  stroke  was  more  efficient,  and  resulted  in  a  cleaner 
hutch-product,  and  relatively  more  of  it,  than  a  longer  stroke 
of  less  frequency,  but  of  the  same  piston-speed. 

E.  Concentration. — If  the  diameters  of  the  grains  of  the  heavy 
mineral  jigged,  and  of  the  bedding-grains  (and  therefore  the 
diameter  of  the  sieve-hole),  do  not  differ  by  any  large  amount,  a 
clean  separation  can    easily  be  made.     With   an  increase  in 
these  ratios,  perfect  separation  is  impossible.     Stated  in  other 
words,  with  bedding  of  a  definite  size,  and  hence  a  fixed  sieve- 
aperture,  the  finer  the  grain  the  more  difficult  is  its  separation 
on  the  jig. 

F.  Specific  Gravity. — Within  rather  wide  limits,  the  difference 
in  the  specific  gravity  of  the  heavier  mineral  paired  with  quartz 
did  not  influence  greatly  the  ease  with  which  it  could  be  sepa- 
rated, or  a  good  concentration  attained. 

4.  Experiments  with  a  6-Sieve  Harz  Jig. 

Two  runs  were  made  as  nearly  as  possible  under  practical 
conditions  to  determine  to  what  extent  the  conclusions  derived 
from  the  Vezin-jig  tests  were  applicable  to  an  ordinary  jig.  The 
ore  used  for  the  work  contained  6  per  cent,  of  mineral — about 
half  sphalerite  and  the  balance  galena,  with  a  quartzose  gangue. 
The  jig  was  bedded  with  material  sized  between  5.2  and  6.6  mm. 
The  first  compartment  was  bedded  with  a  clean  galena,  the 


10  INVESTIGATION    ON   JIGGING. 

second  with  sphalerite,  and  the  third,  fourth,  and  fifth  with 
mixtures  of  sphalerite  and  quartz.  The  thickness  of  the  bed- 
ding averaged  from  20  to  30  mm.  at  the  beginning  of  the  run. 
All  beds  naturally  tended  to  increase  in  thickness,  since  no 
products  were  skimmed  off  during  the  run. 

The  jig  differed  in  no  respect  from  the  common  type  of  Harz 
jig.  Each  sieve-compartment  was  16  by  20  in.  (406  by  512  mm.) 
in  section,  with  pistons  of  equal  area.  The  lengths  of  strokes 
could  be  adjusted  between  limits  of  0  to  50  mm.,  and  within 
a  considerable  range  in  the  number  per  min. — in  the  experi- 
ments, from  175  to  180.  The  actual  piston-speeds  used  ranged 
about  as  follows :  first  compartment,  75  mm. ;  second,  66  to 
70  mm. ;  third,  57  to  67  mm. ;  fourth,  45  to  58  mm. ;  and  fifth, 
45  to  50  mm.  per  sec.  Only  the  hutch-products  and  tailings 
were  examined. 

The  ore,  sized  between  0  and  4.8  mm.,  round  hole,  was 
delivered  to  the  jig  through  a  centrifugal  pump.  All  prod- 
ucts traveled  in  closed  circuits,  and  were  finally  returned  to 
the  centrifugal  elevator  or  pump  to  be  passed  again  over  the 
jig.  The  spigots  constantly  discharged  their  products,  and  from 
these  discharges  time-samples  were  cut  out.  The  run  occu- 
pied exactly  an  hour,  so  that  after  weighing  each  of  the  prod- 
ucts— in  this  case  six — with  the  tailings,  data  were  at  hand  for 
calculating  the  capacities ;  and  after  screening,  weighing,  and 
analyzing,  a  complete  record  of  the  run  was  made.  The  results 
of  these  tests  showed  that  the  differences  in  length  of  stroke, 
or  number  of  strokes  per  rain.,  were  not  sufficient  to  produce  a 
marked  difference  in  the  character  of  the  concentrate;  that 
most  of  the  galena  was  saved  in  the  first  hutch  and  most  of  the 
sphalerite  in  the  second;  that  the  third,  fourth,  and  fifth 
hutches  carried  very  little  galena,  but  more  sphalerite.  It  was. 
found  that  the  first  hutch-product  contained  57  per  cent,  of 
galena,  and  of  this  nearly  70  per  cent,  was  larger  than  1  mm. 
in  diameter;  and  that  sizes  finer  than  this  contained  more 
quartz  and  less  galena.  The  results  seemed  to  indicate  the 
necessity  of  first  removing  stuff  less  than  0.4  mm.  in  diameter 
in  order  to  increase  the  richness  of  the  product.  The  first 
hutch-product  contained  no  coarse  sphalerite,  and  only  when 
the  material  was  as  small  as  0.2  mm.  was  any  considerable 
amount  present.  This  seems  to  indicate  that  an  almost  perfect 


INVESTIGATION    ON   JIGGING.  11 

separation  of  these  two  minerals  (galena  and  sphalerite)  from 
each  other  and  quartz,  under  the  conditions  with  which  the 
jig  was  operated,  was  possible  if  the  feed  had  been  sized 
between  the  limits  of  0.4  and  4.8  mm.  The  second  hutch, 
which  carried  most  of  the  sphalerite,  shows  that  the  coarse 
sizes  pass  through  the  sieve  of  the  jig  less  readily  than  galena. 
Not  until  the  material  was  reduced  to  1.5  mm.  was  any  marked 
percentage  noticeable  in  the  product.  From  0.4  to  1.5  mm. 
most  of  the  saving  was  made.  Evidently,  the  cause  for  so 
little  very  fine  stuff  in  the  second  hutch-product  was  owing  to 
the  fact  that  most  of  it  was  caught  in  the  first.  Under  the  con- 
ditions obtaining  in  the  second  compartment,  a  very  satisfac- 
tory separation  could  be  made  on  all  sizes  below  1.5  mm. 
The  results  from  the  third  compartment  were  like  those  of 
the  second.  The  fourth  and  fifth  hutches  indicated  a  further 
saving  of  sphalerite,  but  between  somewhat  different  size-limits 
than  in  the  second  and  third ;  the  limits  in  the  last  two  com- 
partments varied  between  0.7  and  2.5  mm.,  with  very  little  fine 
stuff'.  This  result  indicates  that  in  the  first  compartments  more 
fine  material  is  present,  making  a  denser  and  more  impervious 
bed,  and  that  the  large  grains  cannot  so  easily  pass  through  it ; 
and  that  in  the  last  compartment  the  bed  is  more  open  and 
porous,  and  hence  larger  grains  can  more  readily  pass  into  the 
hutch.  An  examination  of  the  tailings  indicated  that  the  loss 
in  the  fine  material  was  very  small,  but  by  far  the  largest  loss 
was  in  the  four  coarsest  sizes,  which  were  mixed  grains  or 
middlings,  and  to  reduce  this  loss  further  crushing  must  be 
done.  The  results  indicate  that  in  order  to  separate  sphalerite 
and  quartz,  a  jig  of  at  least  three  compartments  should  be 
used ;  since  smaller  differences  in  the  specific  gravity  of  these 
minerals  require  a  longer  time  to  effect  the  separation.  In  the 
case  of  a  heavy  mineral,  such  as  galena,  one  or  two  compart- 
ments will  effect  a  perfect  separation. 

IV.  EXPERIMENTS  WITH  THE  JARVIS  LABORATORY-JIG. 

In  order  to  investigate  particularly  the  effect  of  pulsion  and 
suction  upon  jigging,  and  upon  accelerated  and  retarded  strokes, 
I  designed  a  special  jig,  with  which  I  conducted  a  series  of  experi- 
ments and  obtained  the  following  results : 


12  INVESTIGATION    ON   JIGGING. 

1.   Construction. 

Figs.  1,  2,  and  3  are  detailed  drawings  of  the  Jarvis  laboratory- 
iig,  with  the  exception  of  the  variable-speed  shaft,  which  is  of 
the  ordinary  disk-and-friction-wheel  pattern.  Figs.  4  and  5  show 
the  designs  of  the  cams  used.  The  screen-area  in  this  jig  is 
8  by  12  in.  (203.2  by  304.8  mm.),  with  a  piston  of  equal  area. 
"With  an  adjustable  dam,  the  height  of  discharge  may  be  varied 
from  3  to  4.5  in.  (76.2  to  114.3  mm.).  In  order  to  study  the 
behavior  of  the  ore-column  and  bedding  during  the  process  of 
jigging,  one  side  of  the  jig-box  was  made  of  plate  glass.  Three 
types  of  strokes  were  employed:  (1)  The  eccentric,  adjustable 
within  the  limits  of  0  and  2  in.  (0  and  50.8  mm.).  (2)  Circu- 
lar-arc cams,  where  the  period  of  pulsion  occupies  three-fourths 
of  the  revolution  of  the  cam,  or  eccentric  shaft,  and  suction  one- 
fourth;  or  by  reversing  the  direction  of  rotation  of  the  cam- 
shaft, or  slipping  the  hub  and  cam  off  the  shaft  and  turning  it 
end  for  end,  the  times  or  periods  are  reversed  respectively  for 
pulsion  and  suction.  Cams  were  made  having  throws  up  to 
2  in.  (50.8  mm.),  but  only  the  three  shortest  throws  were  used — 
namely,  1  in.  (25.4  mm.),  0.5  in.  (12.7  mm.),  and  0.25  in. 
(6.35  mm.).  (3)  Involute  cams,  in  which  the  periods  were 
divided  into  thirds,  i.e.,  one-third  of  the  revolution  of  the  cam- 
shaft devoted  to  pulsion,  and  two-thirds  to  suction ;  or  as  noted 
above,  by  reversing  the  direction  of  rotation  of  the  cam  these 
periods  were  reversed.  All  cams  were  made  of  wood,  and 
quickly  and  easily  attached  to  a  cast-iron  hub,  and  by  means  of  a 
set-screw  fastened  to  the  shaft,  as  shown  in  full  in  Fig.  4.  Circu- 
lar-arc and  involute  cams  indicate  the  character  of  the  curves. 
The  circular-arc  cams  do  not  give  a  uniform  motion ;  or  in  other 
words,  the  cam  in  describing  equal  arcs  in  either  the  pulsion- 
or  suction-period  does  not  cause  the  piston  to  travel  equal  dis- 
tances. In  the  involute  cams,  however,  in  either  pulsion-  or 
suction-periods,  equal  arcs  give  equal  distances  for  piston-travel. 
The  manner  of  communicating  motion  from  the  cams  or  eccen- 
tric is  clearly  indicated  in  Figs.  1  and  2.  These  engage  with 
a  brass  roller  attached  to  a  wrought-iron  yoke  moving  between 
vertical  guides.  In  order  to  steady  and  support  the  yoke  still 
more,  a  steel  rod  is  attached  to  the  upper  end,  passing  through 
a  hole  in  a  cross-beam,  and  is  attached  to  the  lower  end  of  the 
yoke  of  the  piston-rod.  The  roller,  yoke,  and  piston  are  actuated 


— Adjustable  Dam 
•*18Wrt.Iron 


FIG.  1.— THE  JARVIS  LABORATORY- JIG,  LONGITUDINAL  SECTION  AND 
ELEVATION,  AND  PLAN. 


DETAILS  OF  WROUGHT  IRON  YOKE,  ROLLER 
AND  BRACKET 


FIG.  2.— THE  JAR  vis  LABORATORY- JIG,  END  ELEVATION  AND  SECTION,  AND 
DETAILS  OF  YOKE,  ETC. 


INVESTIGATION    ON    JIGGING. 


15 


positively  by  the  cam  on  the  up-stroke,  aud  to  secure  a  strong 
and  quick  down-stroke,  a  spring  of  60  Ib.  pressure  per  linear 
inch  of  compression  was  employed.  This  elastic  pressure 
insured  a  uniform  contact  of  the  roller  and  cam.  It  is  evi- 
dent that  a  large  number  of  styles  of  cam-curves  may  be  used 


DETAILS  OF  REMOVABLE  JIG  BOX,  BOX  MADE  OF  No.24  GAL.  IRON 


DETAIL  OF  ECCENTRIC 
KEY 

FIG.  3.— THE  JARVIS  LABORATORY- JIG,  DETAILS  OF  JiG-Box  AND  ECCENTRIC. 

with  this  device,  and  the  period  of  movement  of  the  piston 
may  be  varied  almost  infinitely.  It  is  to  be  observed,  also,  that 
in  this  system  the  piston,  in  all  positions,  is  perfectly  hori- 
zontal. The  piston  is  made  of  a  single  piece  of  sole-leather, 
securely  riveted  between  two  heavy  plates  of  galvanized  iron. 
With  these  materials  the  piston  can  be  run  with  very  little 


16 


INVESTIGATION    ON    JIGGING. 


CAM  WITH  1  IN.  THROW 


CAM  WITH  X  IN.  THROW 


REAR  ELEVATION 


VERTICAL  SECTION 
THROUGH  A-B 


DETAIL  OF  CAM  HUB 


FIG.  4.— THE  JABVIS  LABORATORY- JIG,  ELEVATIONS  AND  SECTIONS  OF 
CIRCULAR-ARC  WOODEN  CAMS. 

clearance,  and  there  is  no  danger  of  warping,  swelling,  or  get- 
ting out  of  repair  very  easily.    The  hutch-box  sloped  from  three 


INVESTIGATION    ON    JIGGING. 


17 


sides,  at  an  angle  exceeding  50°,  to  a  single  spigot  in  one  side 
of  the  jig.  It  was  found  that  at  this  angle  little  or  no  hutch- 
work  collected  on  the  sides,  and  its  entire  removal  was  easily 
effected.  The  jig  was  driven  by  a  1-h.p.  electric  motor  through 
the  variable-speed  counter-shaft.  The  sieve  was  supported  in 
a  galvanized-iron  skeleton,  which  was  removable  from  the  jig- 
box  itself,  and  different  sized  screens  could  readily  be  inter- 


INVOLUTE,^  IN. 


INVOLUTE,  2  IN. 


INVOLUTE,  \X  IN.  INVOLUTE,  1  IN. 

FIG.  5.— THE  JABVIS  LABORATORY- JIG,  CORVES  OF  INVOLUTE  CAMS. 

changed.     In  the   tests  hereinafter    described,  only  one  size 
sieve — an  8-mesh  one — was  used. 

2.  Materials  and  Other  Accessories. 

A.  Screens. — Table  II.  gives  the  number  and  mesh  of  the 
screen,  and  the  size  of  the  aperture  in  inches  and  millimeters. 
In  all  cases  the  holes  were  square.  The  size  of  the  hole  in  the 
first  five  sizes  was  determined  by  measuring  the  wire^with  a  wire- 


18 


INVESTIGATION    ON    JIGGING. 


gauge,  and  counting  the  number  of  meshes  in  a  given  length. 
For  the  remaining  screens  the  diameter  of  hole  was  determined 
by  measuring  the  diameter  of  the  wire  and  the  aperture  with  a 
microscopic  micrometer,  each  value  given  being  the  mean  of 
several  determinations. 

B.    Sieve-Sizes. — The  data  pertaining  to  the  sieve-sizes  are 
given  in  Table  II. 

TABLE  II. — Sieve-Sizes. 


No. 

Mesh. 

Kind. 

Size  of  Aperture. 

1  

4 
6 
8 
10 
12 
20 
40 
60 
80 
100 

Brass. 
Brass. 
Brass. 
Steel. 
Brass. 
Brass. 
Brass. 
Brass. 
Brass. 
Brass. 

Inch. 
0.2097 
0.1882 
0.0966 
0.0841 
0.0654 
0.0381 
0.0165 
0.0102 
0.0082 
0.0063 

Mm. 
5.326 
3.510 
2.453 
2.136 
1.661 
0.970 
0.420 
0.260 
0.210 
0.160 

2 

3 

4 

5         

6     

7  

8  

9  

10  

Jig-Sieve. 


Steel. 


0.097 


2.464 


C.  Bedding. — The  bedding  used  in  all  the  following  tests  was 
sized  between  the  limits  of  3.510  and  5.326  mm.,  or  through 
the  4-mesh  sieve  and  on  the  6-mesh  sieve,  and  was  maintained 
at  the  same  thickness,  1.5  in.  (38.1  mm.),  upon  the  jig-sieve 
throughout  the  experiments. 

D.  Minerals. — The   three  minerals  used  were   fairly  pure. 
The  quartz  was  kindly  furnished  by  Professor  Munroe,  and  the 
sphalerite  and  galena  by  the  Foote  Mineral  Co.,  of  Philadel- 
phia, Pa. 

E.  Specific  Gravities. — The  specific  gravity  of  each  mineral 
was:  galena,  6.66;  sphalerite,  3.74;  and  quartz,  2.62. 

The  low  specific  gravity  of  the  two  metallic  minerals  indi- 
cates that  they  are  not  pure,  and  an  examination  revealed  the 
presence  of  included  quartz  and  minute  quantities  of  other  min- 
erals. In  crushing  these  minerals,  all  the  quartz  particles  that 
could  be  picked  out  by  hand  were  removed.  The  values  given, 
however,  are  those  obtained  for  the  crushed  minerals,  ready  to 
be  added  to  the  feed. 

These  three  minerals  were  selected  since  zinc-blende  and 
galena  represent  about  the  minimum  and  maximum  limits 


INVESTIGATION    ON    JIGGING. 


19 


respectively  of  the  ores  usually  treated  on  jigs.  In  thus  exam- 
ining the  two  limits,  the  behavior  of  intermediate  minerals 
could  be  closely  predicted. 

F.  Feed. — The  feed  in  all  the  tests  was  crushed  by  stages 
until  small  enough  to  pass  the  lO-mesh  (2.136  mm.)  screen. 
This  size  represented  the  maximum,  from  which  it  varied  to 
that  of  the  finest  dust.  Two  classes  of  feed  were  employed. 
The  first  contained  10  per  cent.,  by  weight,  of  heavy  mineral 
(galena  or  blende),  and  the  second  20  per  cent,  of  heavy  min- 
eral. The  balance  was,  respectively,  90  or  80  per  cent,  of 
quartz.  Table  III.  shows  the  screen-analysis  of  the  three  min- 
erals constituting  the  feed. 

TABLE  III. — Screen-Analysis  of  Minerals  in  Feed. 

All  through  10-mesh 

(2.136    mm.),    and  Through. 

on,  mesh,     ...  12.          20.         40.         60.         80.        100.       100. 

On,  mm.,     ....  1.66      0.97      0.42      0.26      0.21      0.16      0.16 


Per 

Per 

Per 

Per 

Per 

Per 

Per 

Mineral. 

Cent. 

Cent. 

Cent. 

Cent. 

Cent. 

Cent. 

Cent. 

Total. 

Galena,  .     .     . 

.     .        9.6 

23.1 

26.3 

10.8 

5.4 

2.8 

21.2 

99.2 

Sphalerite,  .     . 

.     .      10.5 

24.5 

26.8 

10.5 

5.4 

2.9 

18.6 

99.4 

Quartz,   .     .     . 

.     .      17.1 

29.1 

26.4 

7.5 

4.5 

2.3 

11.0 

99.0 

The  values  in  Table  III.  represent  the  mean  of  three  or  four 
different  determinations,  made  after  crushing  a  large  lot  and 
thoroughly  sampling  it  down. 

Table  IV.  shows  the  calculated  percentages  of  galena  and 
quartz  in  the  two  classes  of  feed,  based  upon  the  screen-analysis 
of  the  pure  minerals  given  in  Table  III. 

TABLE  IV. — Analyses  of  Ten-  and  Twenty-Per  Cent. 
Galena  Feed. 


Ten-Per  Cent.  Galena  Feed. 


M-h-{± 

12. 
1  66 

20. 
0  97 

40. 
0  42 

60. 
0  26 

80. 
0  21 

100. 
0  16 

Thro' 
100. 
0  16 

Average. 

Quartz  
Galena  

Per  Ct. 
94.1 
5.9 

Per  a. 
92.0 
8.0 

Per  Ct. 
90.0 
10.0 

Per  Ct. 
88.8 
11.2 

Per  Ct. 

88.2 
11.8 

Per  Ct. 

88.1 
11.9 

Per  Ct. 
82.3 
17.7 

Per  Ct. 
89.1 
10.9 

Twenty-Per  Cent.  Galena  Feed. 


Quartz 

Per  Ct. 
87.7 

Per  Ct. 
83  4 

Per  Ct. 
80.0 

Per  Ct. 

77.7 

Per  Ct. 

77.3 

Per  Ct. 
76.8 

Per  Ct. 
67.7 

Per  Ct. 

78.7 

Galena  

12.3 

16.6 

20.0 

22.7 

22.3 

23.2 

32.3 

21.3 

20 


INVESTIGATION    ON    JIGGING. 


The  results  obtained  for  sphalerite  and  quartz  are  given  in 
Table  V. 

TABLE  V. — Analyses  of  Ten-  and  Twenty-Per  Cent. 
Sphalerite  Feed. 

Ten-Per  Cent.  Sphalerite  Feed. 


Thro' 

r  inch. 

12. 

20. 

40. 

60. 

80. 

100. 

100. 

Average. 

jyjCS.n.  *\  Tyim 

1  66 

0  97 

0.42 

0  26 

0  21 

0.16 

0.16 

Per  Ct. 

Per  Ct. 

Per  Ct. 

Per  Ct. 

Per  Ct. 

Per  Ct. 

Per  Ct. 

Per  Ct. 

Quartz  

93.6 

91.5 

90.0 

89.2 

88.3 

87.7 

84.6 

89.3 

Sphalerite  

6.4 

8.5 

10.0 

10.8 

11.7 

12.3 

15.4 

10.7 

Twenty-Per  Cent.  Sphalerite  Feed. 


Quartz  

Per  Ct. 

86.7 

Per  Ct. 

82.7 

Per  Ct. 
80.0 

Per  Ct. 
78.3 

Per  Ct. 

77.0 

Per  Ct. 
75.9 

Per  Ct. 
70.4 

Per  Ct. 

78.7 

Sphalerite  

13.3 

17.3 

20.0 

21.7 

23.0 

24.1 

29.6 

21.3 

In  Tables  IV.  and  V.  the  columns  for  each  of  the  respective 
feeds  show  the  percentages  of  each  of  the  two  minerals  on  the 
different  screen-sizes.  Thus,  in  Table  IV.,  with  10  per  cent,  of 
galena,  the  stuff  resting  on  the  12-mesh  (1.66  mm.)  sieve  con- 
tained 94.1  per  cent,  of  quartz  and  5.9  per  cent,  of  galena,  etc. 

With  both  sphalerite  and  galena,  the  screen-analyses,  and 
from  these  the  calculated  percentages  of  the  mineral-content  of 
each  screen-size,  show  that  more  fine  material  is  produced  in 
crushing  these  softer  minerals  than  in  crushing  quartz.  The 
finest  size  of  the  10  and  the  20  per  cent,  galena  or  sphalerite 
shows  a  much  higher  percentage  of  these  minerals  than  the 
average  of  the  feed,  as  shown  in  Tables  IV.  and  V. 

3.  Method  of  Conducting  the  Tests. 

In  beginning  a  series  of  tests  on  a  given  feed,  the  exact  pro- 
portion of  each  mineral  was  weighed  out,  so  that  the  total 
quantity  was  35  Ib.  (15.87  kg.).  Meanwhile,  the  sieve  had 
received  its  bedding,  1.5  in.  (38.1  mm.),  and  the  hutch-box 
and  jig  were  filled  with  water;  the  tailings-trough  placed  in 
position,  connecting  with  a  large  tub  in  which  all  the  overflow 
and  tailings  were  caught ;  the  feed  thoroughly  wetted  down  (it 
fresh  material) ;  power  was  turned  on  and  the  jig  started.  In 
case  it  was  the  first  run  of  a  series,  the  jig-box  containing  bed- 
ding only,  the  feed  was  rapid  until  this  was  filled  with  the  mix- 
ture, after  which  the  feeding  proceeded  at  the  regular  rate. 


INVESTIGATION    ON    JIGGING.  21 

The  feeding  was  accomplished  by  filling  with  the  ore-mixture 
a  large  flat-bottomed  scoop,  of  a  width  slightly  less  than  that 
of  the  jig-compartment,  8  in.  (203.2  mm.),  and  with  a  small 
and  constant  stream  of  water  washing  the  material  from  the 
scoop  on  to  the  jig.  While  the  speed  of  jigging  and  the  rate 
of  feeding  varied,  the  object  always  aimed  at  was  to  feed  the 
jig  just  as  fast  as  it  appeared  able  to  treat  the  material.  The 
discharge  was  watched  constantly  to  see  if  any  particles  of 
heavy  mineral  were  being  carried  into  the  tailings.  If  so,  the 
rate  of  feeding  was  reduced.  Close  watch  was  also  kept  on  the 
jig-bed,  and  if  the  jig  showed  symptoms  of  clogging  up,  due 
to  rapid  feeding,  the  rate  of  feed  was  immediately  decreased. 

At  the  end  of  the  run,  usually  from  8  to  15  min.,  the  jig 
was  stopped,  the  water-supply  cut  off,  and  the  hutch-products 
drawn  off'  into  suitable  vessels.  After  allowing  the  material  to 
settle,  the  water  was  carefully  decanted  and  the  products 
thoroughly  mixed,  and  a  sample  of  about  125  g.  cut  out,  which 
was  dried,  and  later  exactly  100  g.  of  this  sample  was  weighed 
out  on  a  pulp-balance  and  sized  on  a  nest  of  sieves,  ranging 
from  12-mesh  (1.66  mm.)  through  100-mesh  (0.16  mm.),  and 
each  size  carefully  weighed ;  finally,  the  percentage  of  galena 
or  sphalerite  in  each  sieve-size  was  determined.  The  analyses 
of  the  products  were  made  in  several  ways.  In  the  first  two 
or  three  coarse  sizes  good  results  were  obtained  by  weighing 
out  1  or  2  g.  and  picking  out  the  quartz  or  other  mineral  by 
hand  and  then  weighing  again ;  also,  by  comparing  with 
standard  mixtures  of  quartz  and  galena  or  sphalerite.  In  the 
small  sizes  vanning-tests  were  made. 

After  the  completion  of  a  run,  the  tailings,  which  were  given 
ample  time  in  which  to  allow  the  fine  material  to  settle  and 
the  water  to  be  decanted  off",  were  again  mixed  with  the 
product  from  the  hutch  and  formed  the  feed  for  another  test. 
The  material  was  thus  used  repeatedly  until  all  the  tests  had 
been  completed  for  a  particular  series  or  class.  The  material 
remaining  in  the  jig-box  was  not  cleaned  out  from  test  to  test, 
unless  another  feed  was  to  be  employed.  The  investigations 
had  to  do  only  with  what  passed  into  the  hutch,  and  deter- 
minations upon  the  character  and  nature  of  what  remained  on 
the  sieve,  except  as  it  could  be  examined  through  the  glass 
side  of  the  jig,  were  not  made. 


22  INVESTIGATION    ON    JIGGING. 

4.  Record  of  Results. 

In  the  following  records  are  five  horizontal  rows  of  figures : 
in  the  topmost  row,  the  sieve-mesh;  in  the  next  lower  row,  the 
corresponding  size  in  millimeters  of  the  aperture  upon  which 
the  material  was  caught ;  and  three  lower  rows  marked  "  A" 
"  _B,"  and  "  C"  respectively.  The  first  of  these,  A,  gives  the 
weights  in  grams  of  the  different  sieve-sizes ;  and  since  these 
are  all  on  a  basis  of  100  g.  the  weights,  therefore,  represent 
percentages  as  well.  Row  B  gives  the  percentage  of  heavy 
mineral,  galena  or  sphalerite,  in  each  of  the  sieve-products,  and 
the  balance  in  every  case  is  quartz.  Row  C  gives  the  weight 
of  heavy  mineral  contained  in  each  of  the  sieve-sizes,  and  is 
obtained  by  multiplying  the  weights  in  row  A  by  the  respective 
percentages  in  the  B  row.  The  sum  of  the  products  in  the  C 
row  gives  the  number  of  grams  of  mineral  in  100  g.  of  the  con- 
centrate, or  in  other  words,  the  percentage. 

Under  the  stroke  of  each  experiment  are  given:  (1),  the 
number  of  revolutions  of  the  cam  or  eccentric  shaft  per  minute; 
(2)  the  length  in  inches  and  millimeters ;  (3)  the  kind  of  stroke; 
(4)  pulsion,  in  which  the  fractions  £,  £,  £,  f ,  and  £  refer  to  the 
fractional  part  of  the  entire  revolution  of  the  cam  or  shaft  in 
which  this  movement  took  place.  The  smaller  this  fraction  the 
quicker  the  movement.  The  rates  or  velocities  are  set  oppo- 
site. The  same  is  true  for  the  period  of  suction. 

The  observed  pulsion-  and  suction-velocities  noted  in  the  fol- 
lowing tests  and  elsewhere  in  this  paper  are  to  be  understood  as 
the  mean  piston-velocities,  or  the  velocities  of  the  water-column 
in  the  free  part  of  the  jig-column,  and  not  the  actual  current- 
velocities  acting  upon  a  mass  of  grains  constituting  the  jig-bed. 

In  studying  these  experiments,  reference  should  be  made  to 
Figs.  6  to  13,  inclusive,  in  which  row  C  is  shown  graphically 
representing  the  mean  diameter  of  grains. 
TEST  I.— Galena  10,  Quartz  90  per  cent. 

Stroke  :  Cam-shaft  rev.  per  min..  160.     Length,  1  in.  (25.4  mm.). 


Pulsion 
Suction 

Kind: 
:  i  (270.7mm.) 
:  f  (  90.2mm.) 

Circular-arc  cam. 
=  10.66  in.  per  sec. 
=    3.55  in.  per  sec. 

On  mesh  
Size  in  mm.. 

12.           20. 
1.66         0.97 

40.            60.            80. 
0.42          0.26          0.21 

100.  thro'  100. 
0.16          0.16 

Total. 

A.         3.3          11.6 
B.     100.0          80.0 
C.         3.3            9.3 

36.0          18.4           9.5 
35.0          20.0          15.0 
12.6           3.7            1.4 

4.7 
20.0 
0.9 

16.0 
28.0 
4.5 

99.5 

35.7 

INVESTIGATION    ON   JIGGING.  23 

Percentage  of  galena  in  concentrates  :  35.7. 

Katio  of  concentration  based  on  original  feed:  3.57. 

Remarks. — All  the  material  on  the  jig-bed  pulsated— the  material  above  having 
a  longer  amplitude  than  the  grains  deeper  down.  It  was  observed  that  the  bedding- 
grains  at  the  top  moved  nearly  0.75  in.  vertically,  while  those  at  the  bottom  of  the 
bed  next  to  the  screen  moved  about  0.25  in. 

TEST  2. — Galena  10,  Quartz  90  per  cent. 

Stroke  :  Cam-shaft  rev.  per  min.,  160.     Length,  1  in.  (25.4  mm.). 

Kind  :  Circular-arc  cam. 
Pulsion  :  f  (  90.2  mm.)  =    3.55  in.  per  sec. 
Suction:  j  (270.7  mm.)  ==  10.66  in.  per  sec. 


On  mesh  i  12. 
Size  in  mm..ll.66 

20. 
0.97 

40. 
0.42 

60. 
0.26 

80. 
0.21 

100.  thro'  100. 
0.16         0.16 

Total. 

A. 
B. 

a 

0.7 
100.0 
0.7 

7.0 
95.0 
6.6 

26.5 
60.0 
15.9 

22.2 
35.0 

7.7 

14.0 
25.0 
3.5 

6.6 
20.0 
1.3 

22.3 
30.0 
6.7 

99.3 
42.4 

Percentage  of  galena  in  concentrates  :  42.2. 

Ratio  of  concentration  based  on  original  feed  :  4.24. 

Remarks. — Some  movement  of  the  bedding-grains,  especially  near  the  top,  but 
only  a  few  grains  of  galena  were  visible  in  the  interstitial  spaces  of  the  bedding. 
The  ore-column  pulsated  violently,  and  between  the  bedding  and  the  ore  was  a 
zone  in  very  active  motion,  while  above  the  column  of  ore  was  quite  compact. 

TEST  3. — Galena  10,  Quartz  90  per  cent. 

Stroke  :  Cam-shaft  rev.  per  min.,  160.     Length,  1  in.  (25.4  mm.). 

Kind  :  Involute  cam. 
Pulsion  :  £  (203.2  mm.)  =  8  in.  per  sec. 
Suction  :  3  (101.6  mm.)  =  4  in.  per  sec. 


On  mesh.. 
Size  in  mn 

...1  12. 
i.Jl.66 

20. 
0.97 

40. 
0.42 

60. 
0.26 

80. 
0.21 

100.  thro'  100. 
0.16          0.16 

Total. 

A. 
B. 

a 

2.4 
95.0 
2.3 

12.7 
75.0 
10.5 

35.6 
25.0 
8.0 

18.0 
16.0 
3.0 

10.3 
15.0 
1.5 

5.6 
15.0 
0.8 

14.7 
20.0 
2.0 

99.3 
29.9 

Percentage  of  galena  in  concentrates  :  29.9. 

Ratio  of  concentration  based  on  original  feed  :  2.99. 

Remarks. — The  bedding  and  with  it  the  ore-column  pulsated.  The  grains  of 
bedding  were  kept  in  constant  circulation.  Very  few  grains  of  galena  could  be 
seen  in  the  interstitial  spaces  of  the  bedding,  but  were  free.  It  was  evident,  there- 
fore, that  if  a  galena-  or  quartz-grain  got  as  far  as  the  bedding  it  had  little  oppor- 
tunity of  remaining  there.  ' 

TEST  4. — Galena  10,  Quartz  90  per  cent. 

Stroke:  Cam-shaft  rev.  per  min.,  160.     Length,  1  in.  (25.4  mm.). 

Kind  :  Involute  cam. 
Pulsion  :  $  (101.6  mm.)  =  4  in.  per  sec. 
Suction  :  £  (203.2  mm.)  =  8  in.  per  sec. 


On 
Size 

mesh  
in  mm.. 

12. 
1.66 

20. 
0.97 

40. 
0.42 

60. 
0.26 

80. 
0.21 

100.  thro'  100. 
0.16          0.16 

Total. 

A.        0.4 
B.       60.0 
C.         0.2 

7.8 
50.0 
3.9 

39.7 
25.0 
9.9 

21.4 

22.0 
4.7 

10.7 
18.0 
1.9 

4.7 

18.0 
0.8 

14.8 
22.0 
3.2 

99.5 
24.6 

24  INVESTIGATION    ON    JIGGING. 

Percentage  of  galena  in  concentrates  :  24.6. 

Katio  of  concentration  based  on  original  feed  :  2.46. 

Remarks. — The  ore-bed  pulsated  violently,  but  not  so  much  so  as  with  the 
strong  suction  of  the  circular-arc  cam  in  Test  3.  The  grains  of  the  bed  did  not 
behave  exactly  alike,  and  the  middle  of  the  bed  contained  some  grains  of  galena. 

TEST  5. — Galena  10,  Quartz  90  per  cent. 

Stroke  :  Cam-shaft  rev.  per  min.,  160.     Length,  1  in.  (25.4  mm,). 

Kind  :  Eccentric. 
Pulsion  and  Suction  :  }  (135.5  mm.)  =  5.33  in.  per  sec. 


On  mesh  |  12. 
Size  in  mm..  1  1.66 

20. 
0.97 

40. 
0.42 

60. 
0.26 

80. 
0.21 

100.  thro'  100. 
0.16          0.16 

Total. 

A. 
B. 

a 

1.4 
95.0 
1.3 

9.0 
95.0 
8.5 

34.0 
35.0 
11.9 

20.5 
20.0 
4.1 

11.7 
20.0 
2.3 

6.0 
20.0 
1.2 

17.2 
28.0 
4.8 

99.8 
34.1 

Percentage  of  galena  in  concentrates  :  34.1. 

Eatio  of  concentration  based  on  original  feed  :  3.41. 

Remarks. — The  entire  bed  pulsated  much  more  uniformly  than  in  Tests  3  and  4. 
The  bedding-grains  were  free  to  move,  and  tended  to  move  in  convection-currents. 
No  particles  of  galena  collected  on  top  of  the  bedding,  and  few  could  be  seen  in 
the  interstitial  spaces. 

TEST  6. — Galena  10,  Quartz  90  per  cent. 

Stroke  :  Cam-shaft  rev.  per  min.,  160.     Length,  £  in.  (12.7  mm.). 

Kind  :  Eccentric. 
Pulsion  and  Suction  :  £  (67.7  mm.)  =  2.66  in.  per  sec. 


On  mesh  
Size  in  mm.. 

12.           20. 
1.66          0.97 

40. 
0.42 

60. 
0.26 

80. 
0.21 

100.  thro'  100. 
0.16          0.16 

Total. 

A. 
B. 

a 

2.7 

95.0 
2.5 

26.8 
78.0 
20.9 

20.7 
48.0 
9.9 

13.2 
33.0 
4.3 

10.0 
27.0 

2.7 

26.2 
38.0 
9.9 

99.6 
50.2 

Percentage  of  galena  in  concentrates  :  5.02. 

Ratio  of  concentration  based  on  original  feed  :  50.2. 

Remarks. — The  lower  third  of  bedding  quite  fixed,  while  the  upper  two-thirds 
pulsated,  but  the  grains  did  not  change  positions — moving  en  masse.  The  ore- 
column  pulsated  regularly,  and  between  the  beddingand  the  ore  was  a  zone  of  great 
mobility.  The  action  and  movement  going  on  in  the  ore-column  resembled  very 
much  that  taking  place  in  a  hydraulic  classifier. 

TEST  7.—  Galena  10,  Quartz  90  per  cent. 


Stroke  :  Cam-shaft  rev.  per  min.,  160.     Length,  £  in.  (12.7  mm.). 

Kind :  Circular-arc  cam. 
Pulsion  :  J  (135.5  mm.)  =  5.33  in.  per  sec. 
Suction  :  f  (  45.2  mm.)  =  1.77  in.  per  sec. 


On  mesh....j  12. 
Size  in  mm..ll.66 

20. 
0.97 

40. 
0.42 

60. 
0.26 

80. 
0.21 

100.  thro'  100. 
0.16          0.16 

Total. 

A. 

B. 

a 

0.8 
100.0 
0.8 

6.4 
97.0 
6.2 

24.7 
60.0 
14.8 

21.4 
35.0 

7.5 

13.2 
18.0 
2.3 

7.5 
20.0 
1.5 

26.0 
27.0 
7.0 

100.0 
40.1 

INVESTIGATION    ON    JIGGING.  25 

Percentage  of  galena  in  concentrates  :  40.1. 

Ratio  of  concentration  based  on  original  feed  :  4.01. 

Remarks. — The  bedding  and  the  ore-column  pulsated  uniformly — the  top  having 
a  longer  amplitude  and  extending  over  a  longer  time  than  the  grains  nearer  the 
bottom.  Ore-column  very  mobile  and  in  active  circulation.  The  upper  third  of 
bedding  contained  many  particles  of  galena. 

TEST  8.— Galena  10,  Quartz  90  per  cent. 

Stroke  :  Cam-shaft  rev.  per  min.,  160.     Length,  i  in.  (12.7  mm.). 

Kind  :  Circular-arc  cam. 
Pulsion  :  £  (  45.2  mm.)  =  1.77  in.  per  sec. 
Suction  :  }  (135.5  mm.)  =  5.33  in.  per  sec. 


On  mesh... 
Size  in  mm 

.112.           20. 
..11.66         0.97 

40. 
0.42 

60. 
0.26 

80. 
0.21 

100.  thro'  100. 
0.16         0.16 

Total. 

A. 

B. 

C. 

2.1 
90.0 
1.9 

26.0 
53.0 
13.8 

24.4 

31.0 
7.5 

14.7 
20.0 
2.9 

7.1 
20.0 
1.4 

25.3 
27.0 
6.8 

99.6 
34.3 

Percentage  of  galena  in  concentrates  :  34.3. 

Ratio  of  concentration  based  on  original  feed  :  3.43. 

Remarks.— Only  the  top  third  of  bedding  showed  any  signs  of  movement,  but 
the  interstitial  spaces  were  filled  with  particles  of  galena.  The  particles  in  the 
ore-column  tended  to  circulate  in  two  opposite  and  distinct  paths. 

TEST  9. — Galena  10,  Quartz  90  per  cent. 

Stroke  :  Cam-shaft  rev.  per  min.,  160.     Length,  £  in.  (12.7  mm.). 

Kind  :  Involute  cam. 
Pulsion  :  £  (101.6  mm.)  =  4  in.  per  sec. 
Suction  :  f  (  50.8  mm.)  =  2  in.  per  sec. 


On  mesh....:  12. 
Size  in  mm..  1.66 

20. 
0.97 

40. 
0.42 

60. 
0.26 

80. 
0.21 

100.  thro'  100. 
0.16         0.16 

Total. 

A.         1.3 
B.     100.0 
C.        1.3 

10.3 
100.0 
10.3 

27.9 

72.0 
20.0 

20.5 
31.0 
6.3 

11.9 

22.0 
2.6 

6.4 
20.0 
1.3 

21.2 
31.0 
6.5 

99.5 
48.3 

Percentage  of  galena  in  concentrates  :  48.3. 

Ratio  of  concentration  based  on  original  feed  :  4.83. 

Remarks  — Both  the  bedding  and  the  ore-column  pulsated — the  top  having  a 
longer  amplitude  of  vibration  and  requiring  a  longer  time  than  the  grains  nearer 
the  bottom.  Many  grains  of  galena  in  the  upper  third  of  bedding  and  decreasing 
below.  The  ore-column  very  mobile,  and  line  between  bedding  and  ore  hori- 
zontal and  uniformly  even. 

TEST  10.—  Galena  10,  Quartz  90  per  cent. 

Stroke  :  Cam-shaft  rev.  per  min.,  160.     Length,  £  in.  (12.7  mm.). 

Kind  :  Involute  cam. 
Pulsion  :  $  (  50.8  mm.)  =  2  in.  per  sec. 
Suction  :  J  (101.6  mm.)  =  4  in.  per  sec. 


On  mesh....j  12. 
Size  in  mm..|1.66 

20. 
0.97 

40. 
0.42 

60. 
0.26 

80. 
0.21 

100.  thro'  100. 
0.16          0.16 

Total. 

A  
B  
C. 

1.0 
90.0 
0.9 

26.4 
70.0 
20.5 

25.1 
30.0 
7.5 

13.7 

2^.0 
3.8 

7,2 
26.0 
1.8 

26.5 
32.0 
8.5 

99.9 
43.0 

26  INVESTIGATION    ON    JIGGING. 

Percentage  of  galena  in  concentrates  :  43.0. 

Ratio  of  concentration  based  on  original  feed  :  4.30. 

Remarks.— The  bedding-grains  were  practically  stationary— neither  pulsation 
nor  movement  among  themselves,  and  were  filled  with  particles  of  galena.  The 
ore-column  pulsated,  but  was  not  mobile  except  for  a  zone  0.5  in.  teick  on  top  of 
the  bedding.  Evidently  too  much  suction. 

TEST  11.—  Galena  10,  Quartz  90  per  cent. 

Stroke  :  Cam-shaft  rev.  per  min.,  160.     Length,  \  in.  (6.35  mm.). 

Kind  :  Involute  cam. 
Pulsion  :  £  (50.8  mm.)  =  2  in.  per  sec. 
Suction  :  §  (25.4  mm.)  =  1  in.  per  sec. 


On  mesh... 
Size  in  mm. 

.(  12.            20. 
J1.68          0.97 

40. 
0.42 

60. 
0.26 

80. 
0.21 

100.  thro'  100. 
0.16          0.16 

Total. 

A. 
B. 

a 

2.4 
95.0 
2.3 

24.1 
92.0 
22.1 

20.0 
56.0 
11.2 

16.3 
35.0 
5.7 

9.4 
22.0 
2.0 

27.8 
25.0 
5.7 

100.0 
49.0 

Percentage  of  galena  in  concentrates  :  49.0. 

Ratio  of  concentration  based  on  original  feed  :  4.90. 

Remarks. — The  bedding,  as  a  whole,  did  not  pulsate,  but  the  grains  in  the 
upper  part  of  the  bedding  showed  some  movement,  and  this  portion  was  filled 
with  particles  of  galena.  The  ore-column  was  very  mobile  and  pulsated  regu- 
larly and  uniformly.  The  large  grains  of  quartz  rested  directly  upon  the  bed- 
ding, with  the  finer  quartz-particles  above. 

TEST  12. — Galena  10,  Quartz  90  per  cent. 

Stroke  :  Cam-shaft  rev.  per  min.,  160.     Length,  J  in.  (6.35  mm.). 

Kind  :  Involute  cam. 
Pulsion  :  f  (25.4  mm.)  =  1  in.  per  sec. 
Suction  :  J  (50.8  mm.)  =  2  in.  per  sec. 


On  mesh.... 
Size  in  mm... 

12.             20. 
1.66          0.97 

40. 
0.42 

60. 
0.26 

80. 
0.21 

100.  thro'  100. 
0.16          0.16 

Total. 

A. 
B. 

a 

1.4 
80.0 
1.1 

20.4 
62.0 
12.6 

24.5 

40.0 
9.8 

18.8 
27.0 
5.0 

9.1 
24.0 
2.2 

25.5 
25.0 
6.3 

99.7 
37.0 

Percentage  of  galena  in  concentrates  :  37.0. 
Ratio  of  concentration  based  on  original  feed  :  3.7. 

Remarks — The  bedding  did  not  move  at  all.     The  ore-bed  seemed  to  be  quite 
mobile  immediately  above  the  bedding,  but  compact  close  to  the  top. 

TEST  13. — Galena  10,  Quartz  90  per  cent. 

Stroke:  Cam-shaft  rev.  per  min.,  160.     Length,  \  in.  (6.35  mm.). 

Kind  :  Circular-arc  cam. 
Pulsion  :  \  (67.7  mm.)  =  2.66  in.  per  sec. 
Suction  :  £  (22.5  mm.)  =  0.88  in.  per  sec. 


On  mesh.... 
Size  in  mm.. 

12.            20. 
1.66          0.97 

40. 
0.42 

60. 
0.26 

80. 
0.21 

100.  thro'  100. 
0.16          0.16 

Total 

A. 
B. 
C. 

4.2 
95.0 
4.0 

24.8 
62.0 
15.3 

25.5 
26.0 
6.6 

15.1 
20.0 
3.0 

7.3 

18.0 
1.3 

23.1 
27.0 
6.3 

100.0 
36.5 

INVESTIGATION    ON    JIGGING.  27 

Percentage  of  galena  in  concentrates  :  36.5- 

Katio  of  concentration  based  on  original  feed  :  3.65. 

Kemarks. — The  bedding  and  the  ore-column  pulsated,  but  the  grains  of  bedding 
were  not  sufficiently  mobile  to  rearrange  themselves,  although  the  upper  third  was 
much  more  mobile  and  pulsated  much  more  than  the  bottom,  and  many  particles 
of  galena  were  contained  in  the  interstitial  spaces  of  the  upper  third  of  bedding. 
The  entire  ore-column  was  very  free  and  mobile  and  pulsated  uniformly. 

TEST  14. — Galena  10,  Quartz  90  per  cent. 

Stroke  :  Cam-shaft  rev.  per  min.,  160.     Length,  \  in.  (6.35  mm.). 

Kind  :  Circular-arc  cam. 
Pulsion  :  £  (22.5  mm.)  =  0.88  in.  per  sec. 
Suction  :  J  (07.7  mm.)  =  2.66  in  per  sec. 


On  mesh.... 
Size  in  mm.. 

12.           20. 
1.66         0.97 

40. 
0.42 

60. 
0.26 

80. 
0.21 

100.  thro'  100. 
0.16         0.16 

Total. 

A. 
B. 
C. 

2.0 
94.0 
2.0 

24.6 
62.0 
15.2 

22.6 
25.0 
4.6 

14.4 
20.0 
2.9 

7.0 
22.0 
1.5 

29.4 
33.0 
9.7 

100.0 
35.9 

Percentage  of  galena  in  concentrates  :  35.9. 

Eatio  of  concentration  based  on  original  feed  :  3.59. 

Remarks. — No  movement  in  the  bedding,  although  the  top  bedding-grains 
showed  some  tendency  to  move,  and  many  particles  of  galena  could  be  seen  in  the 
upper  third  of  the  bedding.  The  ore-column  pulsated  regularly,  and  was  quite 
compact 

TEST  15. — Galena  10,  Quartz  90  per  cent. 


Stroke  : 
Pulsion 

Cam-shaft  rev.  per  min.,  160.     Length,  \  in.  (6.35  mm.). 
Kind  :  Eccentric, 
and  Suction  :  £  (33.9  mm.)  =  1.33  in.  per  sec. 

On  mesh  
Size  in  mm.. 

12.            20. 
1.66          0.97 

40. 
0.42 

60. 
0.26 

80. 
0.21 

100.  thro 
0.16 

'100. 
0.16 

Total. 

A. 
B. 

a 

0.4 

85.0 
0.3 

17.8 
63.0 
11.2 

23.9 
31.0 
7.4 

17.2 
20.  0 
3.4 

9.3 

20.0 
1.8 

31.0 
30.0 
9.3 

99.6 
33.4 

Percentage  of  galena  in  concentrates  :  33.4. 

Eatio  of  concentration  based  on  original  feed  :  3.34. 

Eemarks. — The  bedding  was  quite  fixed  in  position,  and  the  upper  part  well 
filled  with  grains  of  galena.  It  was  noticed  that  when  the  feed  was  too  fast,  an  in- 
clined line,  beginning  at  the  top  of  the  bedding  at  the  back  of  the  jig-box,  and 
sloping  up  nearly  to  the  top  of  the  ore-column  at  the  front  or  discharge  was 
formed.  Otherwise  the  ore-column  was  mobile,  with  the  coarse  particles  of  quartz 
resting  above  the  bedding,  and  the  finer  particles  arranged  above. 

TEST  16. —  Galena  10,  Quartz  90  per  cent. 

Stroke  :  Cam-shaft  rev.  per  min.,  320.     Length,  J  in.  (6.35  mm.). 

Kind  :  Eccentric. 
Pulsion  and  Suction:  |  (57.7  mm.)  =  2.66  in.  per  sec. 


On  mesh 12.  20.  40.  60.  80  100.  thro' 100.      Total. 

Size  in  mm..  1.66          0.97          0.42          0.26          0.21          0.16          0.16 


A.  0.8  6.4         31.5         26.9         11.9  5.8         16.4          99.7 

B.  100.0          98.0          60.0          25.0          15.0          20.0          30.0 

C.        0.8  6.4         18.9  6.7  1.8  1.1  4.9          40.6 


28  INVESTIGATION    ON    JIGGING. 

Percentage  of  galena  in  concentrates  :  40.6. 

Katio  of  concentration  based  on  original  feed  :  4.06. 

Kemarks.— Both  the  bedding  and  the  ore-column  pulsated  regularly— the  grains 
near  the  top  of  the  bedding  having  a  longer,  amplitude  of  vibration  than  those  near 
the  bottom,  and  the  same  being  true  of  the  grains  in  the  ore-column.  The  ore- 
column  was  very  mobile.  The  jig  worked  fast. 


TEST  17. — Galena  10,  Quartz  90  per  cent. 

Stroke  :  Cam-shaft  rev.  per  min.,  320.     Length,  £  in.  (3.17  mm.). 

Kind  :  Eccentric. 
Pulsion  and  Suction  :  £  (33.9  mm.)  =  1.33  in.  per  sec. 


On  mesh  
Size  in  mm.. 

12.           20. 
1.66          0.97 

40. 
0.42 

60. 
0.26 

80. 
0.21 

100.  thro'  100. 
0.16         0.16 

Total. 

A. 

4.2 

31.3 

27.2 

13.5 

6.4 

17.4 

100.0 

B. 

95.0 

35.0 

21 

.0 

18.0 

18.0 

28.0 

a 

4.0 

10.9 

5.7 

2.4 

1.1 

4.9 

29.0 

Percentage  of  galena  in  concentrates  :  29.0 

Ratio  of  concentration  based  on  original  feed  :  2.90. 

Kemarks.— The  entire  bed  pulsated,  and  the  bedding  contained  many  particles 
of  galena  and  some  quartz.  As  noted  before,  the  top  had  a  longer  amplitude  of 
vibration  than  the  bottom,  and  required  a  longer  time.  The  ore-column  pulsated 
regularly,  and  the  fine  material  (quartz)  was  carried  down  to  the  bedding  so  that 
it  was  distributed  quite  regularly  throughout  the  ore.  The  ore-column  was 
compact. 


TEST  18. — Galena  10,  Quartz  90  per  cent. 

Stroke  :  Cam-shaft  rev.  per  min.,  400.     Length,  ^  in.  (1.59  mm.). 

Kind  :  Eccentric. 
Pulsion  and  Suction  :  £  (21.2  mm.)  =  0.83  in.  per  sec. 


On  mesh  12.           20. 
Size  in  mm..  1.66          0.97 

40. 
0.42 

60. 
0.26 

80. 
0.21 

100.  thro'  100. 
0.16          0.16 

Total. 

A  2.6 

37.3 

26.0 

12.1 

5.8 

16.1 

99.9 

B  100.0 

25.0 

23.0 

16.0 

15.0 

26.0 

a     2.6 

9.3 

6.0 

1.9 

0.8 

4.2 

24.8 

Percentage  of  galena  in  concentrates  :  24.8. 

Ratio  of  concentration  based  on  original  feed  :  2.48. 

Remarks. — The  grains  of  the  bedding  were  not  very  mobile,  and  only  the  top 
layer  of  grains  showed  any  indication  of  pulsating.  The  base  of  the  ore-column 
was  distinguished  by  a  zone  of  active  agitation.  Above  this  zone,  which  was  only 
0.5  in.  thick,  the  ore-column  was  compact  and  not  mobile.  The  bedding-grains 
contained  only  a  few  galena-grains  in  the  upper  third  portion,  but  the  interstitial 
spaces  were  filled  with  quartz.  In  the  middle  and  lower  third  portions  of  the 
bedding,  many  more  grains  of  galena  were  visible,  being  more  abundant  in  the 
middle  third. 


INVESTIGATION    ON    JIGGING.  29 


TEST  21.  —  Galena  20,  Qwarte  80  per  cent. 


Stroke  :  Cam-shaft  rev.  per  min.,  160.     Length,  1 
Kind  :  Circular-arc  cam. 
Pulsion  :  }  (270.7  mm.)  =  10.66  in.  per  sec. 
Suction  :  f  (  90.2  mm.)  =  3.55  in.  per  sec. 

in.  (25.4  mm.). 

On  mesh  1  12.           20.            40.           60.           80. 
Size  in  mm..  1.66          0.97          0.42          0.26          0.21 

100.  thro'  100. 
0.16         0.16 

Total. 

A.        4.3         18.1          33.2         16.7           8.5 
S.     100.0         90.0         55.0         50.0         40.0 
C.        4.3          16.2         18.1            8.5           3.4 

4.0         14.8 
40.0         50.0 
1.6           7.5 

99.6 
59.6 

Percentage  of  galena  in  concentrates  :  59.6. 
Ratio  of  concentration  based  on  original  feed  :  2.98. 
Remarks.  —  Movement  of  jig-bed  same  as  Test  1. 

TEST  22.  —  Galena  20,  Quartz  80  per  cent. 

Stroke  :  Cam-shaft  rev.  per  min.,  160.     Length,  1 
Kind  :  Circular-arc  cam. 
Pulsion  :  f  (90.2  mm)  =  3.55  in.  per  sec. 
Suction  :  J  (270.7  mm.)  =  10.66  in.  per  sec. 

in.  (25.4mm.). 

On  mesh  12.           20.           40.            60.           80. 
Size  in  mm..  1.66        0.97         0.42         0.26'        0.21 

100.  thro'  100. 
0.16         0.16 

Total. 

A.        0.5          6.6         30.4          19.6          11.5 
B.     100.0        90.0          65.0          55.0          45.0 
C.        0.5          5.9          19.5         11.0           5.1 

5.6         25.7 
45.0         50.0 
2.5         12.8 

99.9 
57.3 

Percentage  of  galena  in  concentrates  :  57.3. 
Ratio  of  concentration  based  on  original  feed  :  2.86. 
Remarks.  —  Movement  of  jig-bed  similar  to  Test  2. 

TEST  23.  —  Galena  20,  Quartz  80  per  cent. 

Stroke  :  Cam-shaft  rev.  per  min.,  160.     Length,  1 
Kind  :  Involute  cam. 
Pulsion  :  J  (203.2  mm.)  =  8  in.  per  sec. 
Suction  :  f  (101.6  mm.)  =  4  in.  per  sec. 

in.  (25.4  mm.). 

On  mesh  12.            20.            40.           60.            80. 
Size  in  mm..  1.66          0.97          0.42          0.26          0.21 

100.  thro'  100. 
0.16         0.16 

Total. 

A.        3.4         16.5         32.4         18.0           9.2 
B.     100.0         95.0         55.0         40.0         40.0 
C.         3.4          15.6          17.6            7.2            3.6 

4.3         15.6 
40.0          45.0 
1.6           7.0 

99.4 
56.0 

Percentage  of  galena  in  concentrates  :  56.0. 

Ratio  of  concentration  based  on  original  feed  :  2.80. 

Remarks. — Movement  of  bed  similar  to  Test  3. 


30  INVESTIGATION    ON    JIGGING. 

TEST  24. — Galena  20,  Quartz  80  per  cent. 


Stroke  :  Cam-shaft  rev.  per  min.,  160.     Length,  1  in.  (25.4  mm.). 

.     Kind  :  Involute  cam. 
Pulsion  :  §  (101.6  mm.)  =  4  in.  per  sec. 
Suction  :  £  (203.2  mm.)  =  8  in.  per  sec. 


On  mesh.... 
Size  in  mm.. 

12. 

1.66 

20. 
0.97 

40. 

0.42 

60. 
0.26 

80. 
0.21 

100.  thro'  100. 
0.16          0.16 

Total. 

A.         1.5 
B.       95.0 

a      1.4 

12.2 
80.0 
9.6 

34.0 
56.0 
18.7 

20.0 
45.0 
9.0 

10.2 
40.0 
4.0 

4.8         17.5 
45.0         45.0 

2.1           7.7 

100.2 
52.5 

Percentage  of  galena  in  concentrates  :  52.5. 

Ratio  of  concentration  based  on  original  feed  :  2.62. 

Eemarks. — The  entire  bed  pulsated,  but  not  so  violently  as  No.  23.  The  ore- 
column  pulsated  much  more  than  the  bedding,  and  the  top  of  the  bedding  than  the 
bottom.  Between  the  bedding  and  the  ore-column  was  a  zone  0.5  in.  thick  of 
great  activity.  Few  grains  in  the  interstitial  spaces  of  the  bedding.  Jigged 
rapidly. 

TEST  25. — Galena  20,  Quartz  80  per  cent. 

Stroke  :  Cam-shaft  rev.  per  min.,  160.     Length,  1  in.  (25.4  mm.). 

Kind  :  Eccentric. 
Pulsion  and  Suction  :  £  (135.5  mm.)  =  5.33  in.  per  sec. 


On  mesh.... 
Size  in  mm.. 

12.           20. 
1.66        0.97 

40. 
0.42 

60. 
0.26 

80. 
0.21 

100.  thro'  100. 
0.16         0.16 

Total. 

A. 

4.6         17.4 

28.8 

17.1 

9.5 

5.5 

17.2 

100 

1 

B.     100.0        95.0 

80.0 

50.0 

40.0 

50.0 

45.0 

a 

4.6         17.0 

23.7 

8.5 

3.8 

2.2 

7.6 

67 

4 

Percentage  of  galena  in  concentrates  :  67.4. 

Ratio  of  concentration  based  on  original  feed  :  3.37. 

Remarks.— The  entire  bed  pulsated,  the  upper  part  having  a  longer  amplitude 
of  vibration  and  requiring  a  longer  time  to  complete  it  than  the  grains  nearer  the 
bottom.  Difficult  to  save  the  finest  grains  of  galena.  The  bedding-grains  were 
free  to  change  positions  during  the  pulsion-cycle. 

TEST  26.—  Galena  20,  Quartz  80  per  cent. 

Stroke:  Cam-shaft  rev.  per  min.,  160.     Length,  £  in.  (12.7  mm.). 

Kind:  Eccentric. 
Pulsion  and  Suction  :  $  (67.7  mm.)  =  2.66  in.  per  sec. 


On 

Size 

mesh.... 
in  mm.. 

12. 

1.66 

20. 
0.97 

40. 
0.42 

60. 
0.26 

80. 
0.21 

100.  thro'  100. 
0.16          0.16 

Total. 

A.        0.7 
B.     100.0 
C.         0.7 

7.3 
100.0 
7.3 

26.0 
85.0 
22.1 

16.9 
60.0 
10.2 

11.7 

45.0 
5.4 

7.4 
40.0 

2.8 

•29.5 
40.0 
12.0 

99.5 
60.5 

Percentage  of  galena  in  concentrates  :  60.5 

Ratio  of  concentration  based  on  original  feed  :  3.02. 

Remarks.— The  entire  bed  pulsated,  and  the  zone  between  the  bedding  and  the 


INVESTIGATION    ON    JIGGING.  31 

ore-column  was  an  active  one — the  grains  in  the  ore-column  were  kept  in  constant 
circulation.  The  interstitial  spaces  in  the  upper  third  of  the  bedding  filled  with 
particles  of  galena. 

TEST  27. — Galena  20,  Quartz  80  per  cent. 

Stroke  :  Cam-shaft  rev.  per  min.,  160.     Length,  £  in.  (12.7  mm.). 

Kind  :  Circular-arc  cam. 
Pulsion :  |  (135.5  mm.)  =  5.33  in.  per  sec. 
Suction:  f  (  45.2  mm.)  =  1.77  in.  per  sec. 


On  mesh. 
Size  in  mt 

...   12. 
n..  1.66 

20. 
0.97 

40. 
0.42 

60. 
0.26 

80. 
0.21 

100.  thro'  100. 
0.16         0.16 

Total. 

A. 
B. 

a 

2.4 
100.0 
2.4 

15.0 
100.0 
15.0 

27.9 
85.0 
23.8 

18.4 
50.0 
9.2 

11.4 
35.0 
3.8 

6.0         18.7 
35.0         35.0 
2.1           6.6 

99.8 
62.9 

Percentage  of  galena  in  concentrates  :  62.9. 

Ratio  of  concentration  based  on  original  feed  :  3.15. 

Eemarks. — The  entire  bed  pulsated  very  uniformly,  the  top  having  a  longer 
time  to  complete  it  than  the  grains  nearer  the  bottom.  Many  grains  of  galena  in 
the  upper  part  of  the  bedding,  but  only  a  few  in  the  lower  half. 

TEST  28. — Galena  20,  Quartz  SO  per  cent. 

Stroke  :  Cam-shaft  rev.  per  min.,  160.     Length,  £  in.  (12.7  mm.). 

Kind :  Circular-arc  cam. 
Pulsion  :  f  (  45.2  mm.)  =  1.77  in.  per  sec. 
Suction  :  £  (135.5  mm.)  =  5.33  in.  per  sec. 


On  mesh....]  12. 
Size  in  mm..  1  1.66 

20. 
0.97 

40. 

0.42 

HO. 
0.26 

80. 
0.21. 

100.  thro'  100. 
0.16          0.16 

Total. 

A. 
B. 

a 

0.1 
100.0 
0.1 

1.7 

95.0 
1.7 

25.0 
85.0 
21.2 

22.0 
bO.O 
13.2 

12.7 

45.0 

5.8 

7.3 

45.0 
3.1 

31.2 
45.0 
13.9 

100.0 
59.0 

Percentage  of  galena  in  concentrates:  59.0. 

Ratio  of  concentration  based  on  original  feed  :  2.95. 

Remarks. — The  bedding-grains  did  not  pulsate,  although  those  near  the  top 
exhibited  a  slight  tendency.  The  ore-column  pulsated,  but  excepting  a  zone  about 
0.5  in.  thick  immediately  above  the  bedding  was  otherwise  compact.  The  ore- 
grains  circulated  in  two  distinct  and  opposite  paths. 

TEST  29.— Galena  20,  Quartz  80  per  cent. 

Stroke:  Cam-shaft  rev.  per  min.,  160.     Length,  £  in.  (12.7  mm.). 

Kind  :  Involute  cam. 
Pulsion  :  £  (101.6  mm.)  =  4  in.  per  sec. 
Suction  :  5  (  50.8  mm.)  =  2  in.  per  sec. 


On  mesh....   12.  20.  40.  60.  80.  100.  thro' 100.      Total. 

Size  in  mm..  1.66  0.97  0.42  0.26  0.21  0.16          0.16 

Z        374 16^0  25!  17^2  1L2  6^2         2O7  99^8 

B.  1UO.O  100.0  85.0  60.0  45.0  40.0         45.0 

C.  3.4  16.0  21.2  10.2  4.9  2.4            9.4          67.5 


32  INVESTIGATION    ON    JIGGING. 

Percentage  of  galena  in  concentrates  :  67.5. 

Katio  of  concentration  based  on  original  feed  :  3.37. 

Remarks. — The  entire  bed  pulsated,  the  upper  part,  as  noted  before,  having  a 
longer  amplitude  of  vibration  and  requiring  a  longer  time  to  complete  it  than  the 
grains  beneath.  The  upper  half  of  the  bedding  contained  many  particles  of  galena, 
while  only  a  few  were  visible  in  the  lower  half. 


TEST  30. — Galena  20,  Quartz  80  per  cent. 

Stroke  :  Cam-shaft  rev.  per  min.,  160.     Length,  £  in.  (12.7  mm.). 

Kind  :  Involute  cam. 
Pulsion:  f  (  50.8  mm.)  =  2  in.  per  sec. 
Suction  :  J  (101.6  mm. )  =  4  in.  per  sec. 


On  mesh....   12.  20.  40.  60.  80.          100.  thro' 1 00.      Total. 

Size  in  mm. .1.66          0.97          0.42          0.26          0.21          0.16          0.16 


A.  0.1  3.0          31.3          21.6          11.5  6.5          25.7          99.7 

B.  100.0          95.0          65.0          50.0          40.0          40.0          45.0 

C.  0.1  2.8          20.1          11.0  4.8  2.6          11.7          53.1 

Percentage  of  galena  in  concentrates  :  53.1. 

Katio  of  concentration  based  on  original  feed  :  2.65. 

Kemarks. — The  bedding  exhibited  a  slight  tendency  to  pulsate  en  masse.  The 
upper  part  of  the  bedding  well  filled  with  particles  of  galena,  decreasing  rapidly 
in  number  below.  Immediately  above  the  bedding  the  ore-column  presented  a 
zone  of  active  agitation  about  0.5  in.  thick,  while  above  the  particles  seemed  quite 
compact  and  not  very  mobile. 


TEST  31. — Galena  20,  Quartz  80  per  cent. 

Stroke:  Cam-shaft  rev.  per  min.,  160.     Length,  J  in.  (6.35  mm.). 

Kind  :  Involute  cam. 
Pulsion :  J  (50.8  mm.)  =  2  in.  per  sec. 
Suction  :  f  (25.4  mm.)  =  1  in.  per  sec. 


On  mesh....|  12. 

20. 

40. 

60. 

80. 

100.  thro'  100. 

Total. 

Size  in  mm..|1.66 

0.97 

0.42 

0.26 

0.21 

0.16          0.16 

A  

1.4 

23.0 

17.0 

14.6 

9.0          35.0 

100.0 

B  

100.0 

100.0 

85.0 

60.0 

50.0          45.0 

C. 

1.4 

23.0 

14.4 

8.7 

4.5          15.7 

67.7 

Percentage  of  galena  in  concentrates:  67.7. 

Eatio  of  concentration  based  on  original  feed :  3.39. 

Kemarks.— The  upper  one-third  of  the  bedding-grains  exhibited  some  tendency 
to  arrange  themselves  during  pulsion,  but  the  lower  two-thirds  did  not  move  or 
pulsate.  In  the  upper  third  were  many  particles  of  galena  and  less  below.  The 
ore-column  pulsated  regularly,  the  large  grains  of  quartz  arranging  themselves 
next  to  the  bedding,  the  smaller  on  top.  The  ore-column  was  mobile. 


INVESTIGATION    ON    JIGGING. 

TEST  32. — Galena  20,  Quartz  80  per  cent. 


Stroke  :  Cam-shaft  rev. 
Kind 
Pulsion:  §  (25.4  mm.)  = 
Suction:  J  (50.8  mm.)  = 

per  min.,  160.     Length,  J  in.  (6.35  mm.). 
:  Involute  cam. 
=  1  in.  per  sec. 
=  2  in.  per  sec. 

On  mesh....|  12. 
Size  in  mm..)1.66 

20. 
0.97 

40.            60.           80. 
0.42          0.26          0.21 

100.  thro'  100. 
0.16         0.16 

Total. 

A  
B  

a 

1.2 

90.0 
1.1 

17.5         26.3         15.4 
90.0         55.0         40.0 
15.7         14.3           6.0 

8.7         30.7 
35.0         40.0 
3.1          12.4 

99.8 
52.6 

Percentage  of  galena  in  concentrates  :  52.6. 

Eatio  of  concentration  based  on  original  feed  :  2.63. 

Remarks.— The  bedding  did  not  pulsate.  The  upper  third  was  filled  with  par- 
ticles of  galena  and  decreasing  numbers  below.  The  ore-column  was  somewhat 
mobile  in  spots,  but  pulsated  quite  regularly,  and  on  top  of  the  bedding  was  a 
zone  which  exhibited  considerable  activity. 

TEST  33. — Galena  20,  Quartz  80  per  cent. 


Stroke  : 

Pulsion 
Suction 

Cam-shaft  rev. 
Kind 

:  J  (67.7  mm.) 
:  f  (22.5mm.) 

per  min.,  160.     Length,  £  in. 
:  Circular-  a  re  cam. 
=  2.66  in.  per  sec. 
=  0.88  in.  per  sec. 

(6.35  mm.). 

On  mesh  j  12. 
Size  in  mm..  1.66 

20. 
0.97 

40. 
0.42 

60. 

0.26 

80. 
0.21 

100. 
0.16 

thro'  100. 
0.16 

Total. 

A.        0.4 

B.     100.0 

a      0.4 

5.5 
100.0 
5.5 

27.0 
60.0 
16.2 

24.0 
40.0 
9.6 

13.1 
35.0 
4.5 

6.5 
35.0 
2.3 

23.4 
35.0 
8.0 

99.9 
46.5 

Percentage  of  galena  in  concentrates:  46.5. 

Ratio  of  concentration  based  on  original  feed  :  2.32. 

Eemarks. — The  upper  half  and  often  more  of  the  bedding  pulsated.  In  this 
part,  also,  were  many  particles  of  galena.  The  ore-column  was  mobile,  with  the 
large  quartz-grains  arranged  near  the  top  of  the  bedding  and  the  smaller  sizes 
above. 

TEST  34. — Galena  20,  Quartz  80  per  cent. 


Stroke  :  Cam-shaft  rev. 
Kind: 

per  min.,  160.     Length,  \  in.  (6.35 
Circular-arc  cam. 

mm.). 

Pulsion  :  £  (22.5  mm.)  = 
Suction:  }  (67.7  mm.)  = 

=  0.88  in.  per  sec. 
=  2.66  in.  per  sec. 

On  mesh  j  12. 
Size  in  mm..|1.66 

20. 
0.97 

40. 
0.42 

60. 
0.26 

80. 
0.21 

100. 
0.16 

thro'  100. 
0.16 

Total. 

A. 
B  
C. 

3.0 

100.0 
3.0 

27.7 
85.0 
23.8 

19.2 
70.0 
13.3 

12.3 
50.0 
6.0 

7.2 
50.0 
3.6 

30.5 
45.0 
13.5 

99.9 
63.2 

Percentage  of  galena  in  concentrates  :  63.2. 

Eatio  of  concentration  based  on  original  feed:  3.16. 

Eemarks. — The  bedding  exhibited  very  little  tendency  to  pulsate,  nor  was  there 


34  INVESTIGATION    ON    JIGGING. 

any  movement  among  the  grains  themselves.  The  upper  half  of  the  bedding  was 
well  filled  with  grains  of  galena.  The  particles  of  ore  above  the  bedding  circu- 
lated in  two  opposite  orbits,  passing  down  at  the  front  and  back  end  of  jig  and 
joining  in  the  center. 

TEST  35. — Galena  20,  Quartz  80  per  cent. 

Stroke  :  Cam-shaft  rev.  per  min.,  160.     Length,  \  in.  (6.35  mm.). 

Kind  :  Eccentric. 
Pulsion  and  Suction  :  £  (33.9  mm.)  =  1.33  in.  per  sec. 


On  mesh  
Size  in  mm.. 

12.            20. 
1.66         0.97 

40. 
0.42 

60. 
0.26 

80. 
0.21 

100.  thro'  100. 
0.16          0.16 

Total. 

99JJ 
59.7 

A. 
B. 

a 

0.7 
95.0 
0.7 

17.5 
95.0 
16.6 

19.2 
70.0 
13.3 

18.2 
45.0 
8.1 

8.7 
45.0 
3.5 

35.2 
40.0 
17.5 

Percentage  of  galena  in  concentrates  :  59.7. 

Katio  of  concentration  based  on  original  feed  :  3. 

Kemarks. — The  bedding  pulsated  slightly,  and  the  upper  half  was  well  filled  with 
galena,  with  decreasing  quantities  below.  The  ore-column  pulsated  regularly, 
with  the  largest  grains  of  quartz  resting  on  top  of  the  bedding,  decreasing  in  size 
above. 

TEST  36. — Galena  20,  Quartz  80  per  cent. 

Stroke  :  Cam-shaft  rev.  per  min.,  320.     Length,  \  in.  (6.35  mm.). 

Kind  :  Eccentric. 
Pulsion  and  Suction :  £  (67.  7  mm.)  =  2.66  in.  per  sec. 


On  mesh  
Size  in  mm.. 

12. 
1.66 

20. 
0.97 

40. 
0.42 

KO. 
0.26 

80. 
0.21 

100. 
0.16 

thro'  100. 
0.16 

Total- 

A.         0.6 
S.     100.0 
C.         0.6 

7.2 
100.0 
7.2 

30.1 
65.0 
19.5 

22.8 
45.0 
10.2 

12.3 
40.0 
4.9 

5.6 
40.0 
2.2 

21.2 

50.0 
10.6 

99.8 
55.2 

Percentage  of  galena  in  concentrates  :  55  2. 
Ratio  of  concentration  based  on  original  feed  :  2.76 

Kemarks — The  entire  bed  pulsated  regularly.     The  upper  part  of  bedding  con- 
tained many  particles  of  galena. 

TEST  37. — Galena  20,  Quartz  80  per  cent. 

Stroke  :  Cam-shaft  rev.  per  min.,  320.     Length,  £  in.  (3.17  mm.). 

Kind  :  Eccentric. 
Pulsion  and  Suction  :  £  (33.9  mm.)  =  1.33  in.  per  sec. 


On  mesh  
Size  in  mm.. 

12.            20. 
1.66          0.97 

40. 

0.42 

60. 
0.26 

80. 
0.21 

100.  thro'  100. 
0.16          0.16 

Total. 

A. 
B. 

C. 

10.3 
100.0 
10.3 

27.2 
85.0 
23.1 

23.1 
50.0 
11.5 

13.7 
40.0 
5.5 

7.1 
400 

2.8 

19.0 

40.0 
7.6 

100.4 
60.8 

Percentage  of  galena  in  concentrates  :  60.8. 

Eatio  of  concentration  based  on  original  feed  :  3.04. 

Remarks.— The  upper  third  of  bedding  was  quite  mobile,  and  filled  with  parti- 
cles of  galena,  decreasing  below.  The  ore-column  seemed  quite  compact,  but  pul- 
sated regularly. 


INVESTIGATION    ON    JIGGING.  35 

TEST  38. — Galena  20,  Quartz  80  per  cent. 

Stroke  :  Cam-shaft  rev.  per  min.,  320.     Length,  J  in.  (12.7  ram.). 

Kind  :  Eccentric. 
Pulsion  and  Suction  :  J  (135.5  mm.)  =  5.33  in.  per  sec. 


On  mesh 
Size  in  m 

....  12. 
m..  1.66 

20. 
0.97 

40. 
0.42 

60. 
0.26 

80. 
0.21 

100.  thro'  100. 
0.16         0.16 

Total. 

A. 

B. 

a 

4.3 

100.0 
4.3 

16.4 
95.0 
15.6 

34.6 
50.0 
17.3 

18.2 
40.0 
7.3 

9.0 
35.0 
3.1 

4.6 

40.0 
1.8 

13.2 
4o.O 
5.9 

100.3 
55.3 

Percentage  of  galena  in  concentrates  :  55.3. 

Katio  of  concentration:  2.76. 

Remarks. — Both  ore  and  bedding  pulsated  regularly,  but  violently.  Consider- 
able of  the  finest  size  of  galena  could  be  seen  in  the  tailings.  The  jig  worked 
very  rapidly. 

TEST  41. — Sphalerite  10,  Quartz  90  per  cent. 

Stroke  :  Cam-shaft  rev.  per  min-,  160.     Length,  1  in.  (25.4  mm.). 

Kind  :  Circular-arc  cam. 
Pulsion  :  }  (270.7  mm.)  =  10.66  in.  per  sec. 
Suction  :  f  (  90.2  mm.)  =    3.55  in.  per  sec. 


On  mesh  
Size  in  mm.. 

12 
1.66 

20. 
0.97 

40. 
0.42 

60. 
0.26 

80. 
0.21 

100. 
0.16 

thro'  100. 
0.16 

Total 

A.       11.8 
B.       20.0 
C.        2.4 

31.8 
20.0 
6.4 

30.2 
25.0 
7.5 

11.0 
30.0 
3.3 

5.0 

35.0 
1.7 

2.2 

40.0 
0.8 

5.2 
50.0 
2.6 

97.2 

24.7 

Percentage  of  sphalerite  in  concentrates  :  24.7. 

Ratio  of  concentration  based  on  original  feed  :  2.47. 

Remarks  — The  bedding  pulsated  very  violently,  and  after  the  jig  was  stopped 
it  was  found  that  the  surface  of  the  ore-column  was  1.5  in.  below  the  tail- 
ings-dam. 

TEST  42. — Sphalerite  10,  Quartz  90  per  cent. 

Stroke  :  Cam-shaft  rev.  per  min.,  160.     Length,  1  in.  (25.4  mm.). 

Kind  :  Circular-arc  cam. 
Pulsion:  f  (  90.2  mm.)  =    3.55  in.  per  sec. 
Suction  :  j  (270.7  mm.)  =  10.66  in.  per  sec. 


On  mesh  
Size  in  mm.. 

12. 
1.66 

20. 
0.97 

40. 
0.42 

60. 
0.26 

80. 
0.21 

100. 
0.16 

thro'  100. 
0.16 

Total 

A.        3.6 
B.       60.0 
C.        2.1 

14.1 

65.0 
9.1 

36.5 
35.0 
12.7 

19.2 
30.0 
5.7  • 

9.5 
35.0 
3.3 

4.5 
30.0 
1.4 

12.2 
40.0 
5.0 

99.6 

39.3 

Percentage  of  sphalerite  in  concentrates  :  39.3. 

Ratio  of  concentration  based  on  original  feed:  3.93. 

Remarks. — The  bedding-grains  were  carried  up  from  bottom  to  top,  circu- 
lating in  that  way  as  by  convection-currents.  The  ore-column  was  in  active  agi- 
tation, and  the  bedding  and  the  ore  were  not  separated  by  a  clearly  denned  and 
horizontal  line. 


36  INVESTIGATION    ON    JIGGING. 

TEST  43.  -Sphalerite  10,  Quartz  90  per  cent. 

Stroke  :  Cam-shaft  rev.  per  min.,  160      Length,  1  in.  (25.4  mm  ). 

Kind  :  Involute  cam. 
Pulsion  :  J  (203.2  mm.)  =  8  in.  per  sec 
Suction  :  f  (101.6  mm.)  =  4  in.  per  sec. 


On  mesh.... 
Size  in  mm.. 

12. 
1.66 

20. 
0.97 

40. 
0.42 

BO. 

0.26 

80. 
0.21 

100.  thro'  100. 
0.16          0.16 

Total. 

A.        7.6 
B.       25.0 
C.         1.9 

26.5 
35.0 
9.2 

34.5 
25.0 
8.6 

13.7 

25.0 
3.4 

6.7 
35.0 
2.2 

3.1 
30.0 
0.9 

8.1 
40.0 
3.2 

100.2 
29.4 

Percentage  of  sphalerite  in  concentrates  :  29.4. 

Katio  of  concentration  based  on  original  feed  :  2.94. 

Remarks.  —  The  jig-bed  pulsated  violently.  The  bedding  did  not  tend  to  move 
in  convection-currents,  as  in  Test  42.  Between  the  bedding  and  the  ore-column  was 
a  very  active  zone  0.5  in  wide,  in  which  the  mineral  particles  moved  in  all  direc- 
tions and  with  great  rapidity. 

TEST  44.  —  Sphalerite  10,  Quartz  90  per  cent. 

Stroke  :  Cam-shaft  rev.  per  min  ,  160      Length,  1  in.  (25.4  mm.). 

Kind  :  Involute  cam. 
Pulsion  :  §  (101.6  mm.)  =  4  in.  per  sec. 
Suction  :  £  (203.2  mm.)  =  8  in.  per  sec. 


On  mesh....l  12. 
Size  in  mm..|1.66 

20.. 
0.97 

40. 
0.42 

60. 

0.26 

80. 
0.21 

100.  thro'  100. 
0.16          0.16 

Total. 

A. 

B. 

0. 

3.4 
85.0 
3.0 

17.5 

60.0 
10.5 

40.1 
30.0 
12.0 

17.1 
.    25.0 
4.2 

8.7 
35.0 
2.9 

4.0 
30.0 
1.2 

9.2 
40.0 
3.8 

100.0 
37.6 

Percentage  of  sphalerite  in  concentrates  :  37.6 

Katio  of  concentration  based  on  original  feed  :  3.76. 

Remarks.— The  movement  of  the  jig-bed  was  very  similar  to  Test  42.  The  bed- 
ding-grains were  not  only  carried  from  the  bottom  of  the  bedding-column  itself, 
but  many  rose  to  the  top  of  the  ore-column,  and  a  few  of  the  lightest  were  carried 
off  with  the  tailings.  The  grains  of  quartz  could  be  seen  very  plainly  rolling 
down  with  the  larger  bedding-grains  and  being  carried  into  the  hutch. 

TEST  45. — Sphalerite  10,  Quartz  90  per  cent. 


Stroke:  Cam-shaft  rev.  per  min.,  160.     Length,  1  in.  (25.4  mm.). 

Kind  :  Eccentric. 
Pulsion  and  Suction  :  £  (135.5  mm.)  =  5.33  in.  per  sec. 


On  mesh.... 
Size  in  mm.. 

12. 
1.66 

20. 
0.97 

40. 
0.42 

60. 
0.26 

80. 
0.21 

100.  thro'  100. 
0.16          0.16 

Total. 

A.         5.3 
B.      85.0 
O.        4.6 

17.0 
80.0 
13.6 

32.2. 
45.0 
14.4 

18.0 
40.0 

7.2 

9.2 
35.0 
3.3 

4.7 
40.0 
1.8 

13.3 

45.0 
5.8 

99.7 
50.7 

Percentage  of  sphalerite  in  concentrates  :  50.7. 
Ratio  of  concentration  based  on  original  feed  :  5.07. 

Remarks.— Both  the  bedding  and  the  ore-column  pulsated  regularly.     Each 
formed  distinct  and  well-defined  layers.     The  jig  worked  very  rapidly. 


INVESTIGATION    ON    JIGGING.  37 

TEST  46. — Sphalerite  10,  Quartz  90  per  cent. 


Stroke  :  Cam-shaft  rev. 
Kind 

per  rain.,  160.     Length,  £  in.  (12.7  m 
:  Eccentric. 

.m.). 

Pulsion  and  Suction  £  (67.7  mm.; 

i  =  2.66  in.  per  sec. 

On  mesh. 

...i  12. 

20. 

40. 

60. 

80.            100.  thro'  100. 

Total. 

Size  in  mm..  1.66 

0.97 

0.42 

0.26 

0.21 

0.16 

0.16 

A. 

3.4 

15.7 

29.7 

19.0 

11.4 

5.8 

15.0 

100.0 

B. 

100.0 

90.0 

50.0 

35.0 

30.0 

30.0 

40.0 

a 

3.4 

14.4 

15.0 

6.6 

3.3 

1.8 

6.0 

50.5 

Percentage  of  sphalerite  in  concentrates  :  50.5. 

Ratio  of  concentration  based  on  original  feed  :  5.05. 

Remarks. — The  upper  half  to  three-fourths  of  the  bedding  pulsated  regularly, 
the  bottom  grains  were  almost  stationary.  The  lower  part  of  the  ore- column  con- 
sisted of  the  largest  particles  of  quartz,  with  smaller  and  smaller  giains  to  the  top. 

TEST  47. — Sphalerite  10,  Quartz  90  per  cent. 


Stroke  :  Cam-shaft  rev. 
Kind 
Pulsion  :  J  (135.5  mm. 
Suction  :  f  (  45.2  mm.) 

per  min.,  ItiO.     Length,  £  in.  (12.7  i 
:  Circular-arc  cam. 
)  =  5.33  in.  per  sec. 
=  1.77  in.  per  sec. 

mm.). 

On  mesh....|  12. 
Size  in  mm.  .|  1.66 

20. 
0.97 

40. 
0.42 

60. 
0.26 

80. 
0.21 

100.  thro'  100. 
0.16          0.16 

Total. 

A. 

7.0 

19.8 

34.0 

18.8 

8.5 

3.7 

8.0 

99.8 

B. 

60.0 

55.0 

30.0 

25.0 

30.  0 

30.0 

40.0 

a 

4.2 

11.0 

10.2 

4.7 

2.5 

1.2 

3.2 

37.0 

Percentage  of  sphalerite  in  concentrates  :  37.0. 

Ratio  of  concentration  based  on  original  feed  :  3.70. 

Remarks. — The  entire  bed  moved  en  masse,  the  top  of  the  column  having  a 
longer  amplitude  of  vibration  and  requiring  a  longer  time  for  its  completion  than 
the  grains  nearer  the  bottom.  The  jig  worked  rapidly. 

TEST  48. — Sphalerite  10,  Quartz  90  per  cent. 

Stroke :  Cam-shaft  rev.  per  min.,  ICO.     Length,  J  in.  (12.7  mm.). 

Kind  :  Circular-arc  cam. 
Pulsion  :  f  (  45.2  mm.)  =  1.77  in.  per  sec. 
Suction  :  J  (135.5  mm.)  =  5.33  in.  per  sec. 


On  mesh....|  12. 
Size  in  mm..  [  1.66 

20. 
0.97 

40. 
0.42 

60. 
0.26 

80. 
0.21 

100.  thro'  100. 
0.16          0.16 

Total. 

A. 

1.1 

7.0 

35.0 

24.6 

12.2 

5.1 

15.0 

100.0 

B. 

90.0 

75.0 

30.0 

25.0 

30.0 

30.0 

35.0 

C. 

1.0 

5.2 

10.5 

6.2 

3.6 

1.5 

5.2 

33.2 

Percentage  of  sphalerite  in  concentrates  :  33.2. 

Ratio  of  concentration  based  on  original  feed  :  3.32. 

Remarks. — The  bedding  pulsated,  but  not  regularly,  and  tended  to  thicken  in 
the  middle  and  thin  down  at  the  ends.  The  grains  at  the  bottom  of  the  ore- 
column  were  in  very  active  agitation,  but  it  was  found  that  these  grains  were  really 
describing  two  distinct  orbits. 


38  INVESTIGATION    ON    JIGGING. 

TEST  49. — Sphalerite  10,  Quartz  90  per  cent. 

Stroke  :  Cam  shaft  rev.  per  min.,  160.     Length,  £  in.  (12.7  ram.). 

Kind  :  Involute  cam. 
Pulsion  :  J  (101.6  mm.)  =  4  in.  per  sec. 
Suction  :  §  (  50.8  mm.)  =  2  in.  per  sec. 


On  mesh. 
Size  in  mr 

...1  12. 
a.Jl.66 

20. 

0.97 

40. 
0.42 

60. 
0.26 

80. 

0.21 

100.  thro'  100. 
0.16          0.16 

Total. 

A. 
B. 

C. 

9.6 

50.0 

4.8 

20.0 
65.0 
13.0 

31.0 
35.0 
10.8 

18.5 
25.0 
4.2 

8.5 
30.0 
2.5 

3.7 
30.0 
1.1 

7.3 

40.0 
2.8 

98.6 
39.2 

Percentage  of  sphalerite  in  concentrates  :  39.2. 

Ratio  of  concentration  based  on  original  feed  :  3.92. 

Remarks. — The  upper  two-thirds  of  the  bedding  and  the  entire  ore-column 
pulsated  regularly.  As  noted  before,  the  grains  nearest  the  top  had  a  longer  am- 
plitude of  vibration  and  required  a  longer  time  to  complete  it.  The  lower  one- 
third  of  the  bedding  was  quite  stationary. 

TEST  50. — Sphalerite  10,  Quartz  90  per  cent. 

Stroke  :  Cam-shaft  rev.  per  min.,  160.     Length,  f  in.  (12.7  mm.). 

Kind  :  Involute  cam. 
Pulsion  :  £  (  50.8  mm.)  =  2  in.  per  sec. 
Suction  :  £  (101.6  mm.)  =  4  in.  per  sec. 


On  mesh.... 
Size  in  mm.. 

12. 
1.66 

20. 
0.97 

40. 
0.42 

60. 
0.26 

80. 
0.21 

100.  thro'  100. 
0.16          0.16 

Total. 

A.        0.8 
B.     100.0 
C.         0.8 

8.7 
65.0 

5.8 

41.4 

25.0 

10.2 

22.0 
25.0 
5.5 

10.0 
25.0 
2.5 

4.8 
35.0 
1.6 

11.6 
40.0 
4.6 

99.3 
31.0 

Percentage  of  sphalerite  in  concentrates  :  31.0. 

Ratio  of  concentration  based  on  original  feed  :  3.1. 

Remarks. — The  bedding  pulsated  slightly,  and  the  grains  shifted  positions  as  in 
convection-currents.  A  zone  between  the  bedding  and  the  ore-column  moved 
much  as  noted  in  Test  40.  The  ore-column  above  this  zone  pulsated  regularlv, 
although  the  ore-column  was  not  very  mobile. 

TEST  51. — Sphalerite  10,  Quartz  90  per  cent. 

Stroke  :  Cam-shaft  rev.  per  min.,  160.     Length,  J  in.  (6.35  mm.). 

Kind  :  Circular- arc  cam. 
Pulsion  :  \  (67.7  mm.)  =  2.66  in.  per  sec. 
Suction  :  f  (22.5  mm.)  =  0.88  in.  per  sec. 


On  mesh. 
Size  in  mi 

....   12. 
n..il.66 

20. 
0.97 

40. 
0.42 

60. 
0.26 

80. 
0.21 

100.  thro'  100. 
0.16          0.16 

Total. 

A. 
B. 

a 

1.4 
90.0 
1.2 

9.5 

80.0 
7.6 

44.5 
25.0 
11.0 

22.2 

25.0 
5.5 

9.4 
35.0 
3.2 

4.6 
30.0 
1.5 

8.0 
35.0 

2.8 

99.6 
32.8 

Percentage  of  sphalerite  in  concentrates  :  32.8. 

Ratio  of  concentration  based  on  original  feed  :  3.28. 

Remarks.— The  bedding  and  with  it  the  ore-column  pulsated  en  masse.  Taking 
the  entire  column  of  bedding  and  ore  as  a  whole,  the  top  had  a  much  longer  am- 
plitude of  vibration,  and  required  a  longer  time  in  which  to  complete  it. 


INVESTIGATION    ON    JIGGING.    >  39 

TEST  52. — Sphalerite  10,  Quartz  90  per  cent. 


Stroke  :  Cam-shaft  rev.  per  min.,  160.     Length,  J  in. 
Kind  :  Circular-arc  cam. 
Pulsion  :  f  (22.5  mm.)  =  0.88  in.  per  sec. 
Suction  :  J  (67.7  mm.)  =  2.66  in.  per  sec. 

(6.35  mm.). 

On  mesh  '  12.            20.            40.            60.            80. 
Sizeinmm..;1.66          0.97          0.42          0.26          0.21 

100.  thro'  100. 
0.16          0.16 

Total. 

A.        2.0         11.6         31.8         22.7          11.6 
B.     100.0         95.0         45.0         35.0         35.0 
C.         2.0          11.0          14.4            8.0            4.2 

5.5          14.6 
35.0          35.0 
1.6            4.9 

99.8 
46.1 

Percentage  of  sphalerite  in  concentrates  :  46.1. 
Ratio  of  concentration  based  on  original  feed  :  4.61. 
Remarks.  —  Movement  of  jig-led  very  similar  to  that  of  Test  48,  but  to 
extent. 

TEST  53.  —  Sphalerite  10,  Quartz  90  per  cent. 

a  less 

Stroke  :  Cam-shaft  rev.  per  min.,  160.     Length,  \  in. 
Kind  :  Involute  cam. 
Pulsion  :  £  (50.8  mm.)  =  2  in.  per  sec. 
Suction  :  §  (25.4  mm.)  =  1  in.  per  sec. 

(6.35  mm.). 

On  mesh  1  12.            20.           40.           60.            80. 
Size  in  mm..'  !.66          0.97          0.42          0.26          0.21 

100.  thro'  100. 
0.16         0.16 

Total. 

A.        0.6           9.8         30.0         23.8         13.0 
B.     100.0          90.0          55.0          40.0          35.0 
C.         0.6            9.0          16.5            9  5            4.5 

7.5          14.8 
30.0         35.0 
2.1           5.2 

99.5 

47.4 

Percentage  of  sphalerite  in  concentrates  :  47.4. 

Ratio  of  concentration  based  on  original  feed  :  4.74. 

Remarks.  —  The  bedding  pulsated  in  the  upper  third  and  half,  and  was  quite 
mobile  as  well.  The  lower  part,  however,  was  stationary.  The  line  between  bed- 
ding and  ore  was  horizontal  and  straight.  The  ore-column  pulsated  regularly  — 
the  top  for  a  greater  distance,  and  for  a  longer  time,  as  before. 

TEST  54.  —  Sphalerite  10,  Quartz  90  per  cent. 


Stroke  :  Cam-shaft  rev. 
Kind 
Pulsion  :  $  (25.4mm.)  = 
Suction  :  £  (50.8mm.)  = 

per  min.,  160.     Length,  }  in.  (6.35  mm.). 
:  Involute  cam. 
=  1  in.  per  sec. 
=  2  in.  per  sec. 

On  mesh  12. 
Size  in  mm..  1.66 

20. 
0.97 

40. 
0.42 

60. 
0.26 

80. 
0.21 

100. 
0.16 

thro'  100. 
0.16 

Total. 

A. 
B. 

0.8 
100.0 
0.8 

5.4 

90.0 
4.8 

31.2 
50.0 
15.5 

30.0 
8.6 

35.0 
4.5 

6.7 
30.0 
2.1 

14.7 
35.0 
4.9 

100.9 
41.2 

Percentage  of  sphalerite  in  concentrates  :  41.2. 

Ratio  of  concentration  based  on  original  feed  :  4.12. 

Remarks.  —  The  entire  bedding  was  practically  stationary,  did  not  pulsate,  nor 
was  it  mobile.  The  interstitial  spaces  in  the  upper  part  of  bedding  filled  with 
grains  of  sphalerite.  The  ore-column  pulsated  en  masse  and  was  fairly  mobile. 


40  INVESTIGATION    ON    JIGGING. 

TEST  55. — Sphalerite  10,  Quartz  90  per  cent. 

Stroke  :  Cam-shaft  rev.  per  min.,  160.     Length,  \  in.  (6.35  mm.). 

Kind  :  Eccentric. 
Pulsion  and  Suction  :  }  (33.9  mm.)  =  1.33  in.  per  sec. 

On  mesh I  12.  2O  4o!  fio! 8O  100.  thro' 100.     Total. 

Size  in  mm.. |l. 66          0.97          0.42          0.26          0.21          0.16          0.16 

~A.         04  7/7          2972 HM5          ISXJ 8^2 19^5          997e 

R.       90.0          95.0          70.0          45.0          40.0          35.0          35.0 
C.        0.4  7.3          20.6  9.0  6.0  2.8  6.6          52.7 

Percentage  of  sphalerite  in  concentrates  :  52.7. 

Katio  of  concentration  based  on  original  feed  :  5.27. 

Eemarks. — The  upper  third  of  the  bedding  was  mobile,  but  the  lower  two-thirds 
was  quite  fixed.  The  ore-column  pulsated  regularly,  together  with  the  upper 
third  of  bedding.  The  line  between  the  ore-column  and  the  bedding  was  clearly 
marked. 


TEST  61.  —  Sphalerite  20,  Quartz  80  per  cent. 

Stroke  :  Cam-shaft  rev.  per  min.,  160.     Length,  1  in.  (25.4  mm.). 

Kind  :  Circular-arc  cam. 
Pulsion  :  }  (270.7  mm.)  =  10.66  in.  per  sec. 
Suction  :  f  (  90.2  mm.)  =  3.55  in.  per  sec. 


On  mesh  I  12. 
Size  in  mm..!  1.66 

20. 
0.97 

40. 
0.42 

60. 

0.26 

80. 
0.21 

IOO.thro'100. 
0.16          0.16 

Total. 

A. 
B. 
C. 

6.3 
45.0 

2.7 

28.2 
35.0 
9.8 

33.6 
30.0 
10.0 

12.6 
30.0 

3.8 

6.0 
35.0 
2.1 

2.7 
40.0 
1.0 

9.8 
50.0 
4.5 

99.2 
33.9 

Percentage  of  sphalerite  in  concentrates  :  33.9. 

Ratio  of  concentration  based  on  original  feed  :  1.7. 

Remarks.  —  The  entire  jig-bed  pulsated  very  violently.  The  feed  was  very  fast, 
a  large  amount  of  hutch-work  was  made,  and  the  tailings  contained  considerable 
fine  mineral.  The  fine  quartz  could  be  seen  sifting  through  the  bedding. 

TEST  62.  —  Sphalerite  20,  Quartz  80  per  cent. 


Stroke  :  Cam-shaft  rev.  per  min.,  160.     Length,  1  in.  (25.4  mm.). 

Kind  :  Circular-arc  cam. 
Pulsion  :  f  (  90.2  mm.)  =  3.55  in.  per  sec. 
Suction  :  J  (270.7  mm.)  =  10.66  in.  per  sec. 


On  mesh 12.  20.  40.  60.  80.  IOO.thro'100.     Total- 

Size  in  mm..  1.66          0.97          0.42         0.26          0.21          0.16          0.16 


A.         1.9          13.2          38.0          18.3  9.7  4.6          14.0          99.7 

S.       90.0          75.0          35.0          40.0          40.0          50.0          50.0 
C.         1.8  9.7          13.3  7.4  3.8  2.3  7.0          45.3 

Percentage  of  sphalerite  in  concentrates  :  45.2. 
Ratio  of  concentration  based  on  original  feed  :  2.26. 
Remarks.— Behavior  of  jig-bed  similar  to  Test  41. 


INVESTIGATION    ON    JIGGING. 


41 


TEST  63.  —  Sphalerite  20,  Quartz  80  per  cent. 

Stroke  :  Cam-shaft  rev.  per  min.,  160.     Length,  1  in.  (25.4  mm.). 

Kind  :  Involute  cam. 
Pulsion  :  £  (203.2  mm.)  ==  8  in.  per  sec. 
Suction  :  f  (101.6  mm.)  =  4  in.  per  sec. 


On 
8ia 

mesh  
j  in  mm.. 

12. 
1.66 

20. 
0.97 

40. 
0.42 

60. 
0.26 

80. 
0.21 

100.  thro'  100. 
0.16          0.16 

Total. 

A.        4.8 
J?.       70.0 

a      3.3 

21.5 

50.0 
10.7 

36.8 
35.0 
12.9 

15.1 
40.0 
6.0 

7.8 
45.0 
3.4 

3.3 

50.0 
1.6 

10.2 
60.0 
6.0 

99.5 
43.9 

Percentage  of  sphalerite  in  concentrates  :  4H.9. 
Eatio  of  concentration  based  on  original  feed  :  2.20. 
Remarks. — Behavior  of  jig-bed  similar  to  Test  43. 

TEST  64. — Sphalerite  20,  Quartz  80  per  cent. 

Stroke  :  Cam-shaft  rev.  per  min.,  160.     Length,  1  in.  (25.4  mm.). 

Kind  :  Involute  cam. 
Pulsion  :  §  (101.6  mm.)  =  4  in.  per  sec. 
Suction  :  £  ('/03.2  mm.)  =  8  in.  per  sec. 


On  mesh  
Size  in  mm.. 

12. 
1.66 

20. 
0.97 

40. 
0.42 

60. 
0.26 

80. 
0.21 

100.  thro'  ICO. 
0.16          0.16 

Total. 

A.         2.3 

B.       85.0 

a      1.9 

17.2 
45.0 
7.6 

37.8 
35.0 
13.1 

17.3 
40.0 
6.8 

8.5 
40.0 
8.4 

4.1 
50.0 
2.0 

12.8 
55.0 
6.8 

100.0 
41.6 

Percentage  of  sphalerite  in  concentrates  :  41.6. 
Ratio  of  concentration  based  on  original  feed  :  2.08. 
Remarks  — Movement  of  jig-bed  similar  to  Test  44. 

TEST  65. — Sphalerite  20,  Quartz  80  per  cent. 

Stroke  :  Cam-shaft  rev.  per  min.,  160.     Length,  1  in.  (25.4  mm.). 

Kind  :  Eccentric. 
Pulsion  and  Suction :  }  (135.5  mm.)  =  5.33  in.  per  sec. 


On 
Siz< 

mesh.... 
j  in  mm.. 

12. 
1.66 

20. 
0.97 

40. 
0.42 

ilO. 

0.26 

80. 
0.21 

100. 
0.16 

thro'  100. 
0.16 

Total. 

A.        2.5 
B.       90.0 

a      2.2 

14.2 

80.0 
11.2 

34.6 
50.0 
17.2 

18.6 
40.0 
7.4 

10.0 
4x0 
4.5 

4.5 
50.0 
2.2 

15.0 
60.0 
9.0 

99.4 
53.7 

Percentage  of  sphalerite  in  concentrates  :  53.7. 
Ratio  of  concentration  based  on  original  feed  :  2.7. 
Remarks — Movement  of  jig-bed  similar  to  Test  45. 

TEST  66. — Sphalerite  20,  Quartz  80  per  cent. 

Stroke  :  Cam-shaft  rev.  per  min.,  160.     Length,  £  in.  (12.7  mm.). 

Kind  :  Eccentric. 
Pulsion  and  Suction  :  £  (67.7  mm.)  =  2.66  in.  per  sec. 

On  mesh.... I  12.  20.  40.  60.  80.  100.  thro'100. 

Size  in  mm..  1.66          0.97          0.42          0.26          0.21          0.16          0.16 


Total. 


A.  2.5          12.4 

B.  90.0          85.0 

C.  2.2          10.5 


3^.0 
60.0 

'20.0 


19.0 
45.0 

8.5 


11.0  4.9          17.2 

45.0          50.0         50.0 

5.0  2.5  8.6 


100.0 
57.3 


42  INVESTIGATION    ON    JIGGING.      , 

Percentage  of  sphalerite  in  concentrates  :  57.3. 
Ratio  of  concentration  based  on  original  feed  :  2.8. 
Remarks. — Movement  of  jig-bed  similar  to  Test  46. 

TEST  67. — Sphalerite  20,  Quartz  80  per  cent. 

Stroke:  Cam-shaft  rev.  per  min.,  160.     Length,  £  in.  (12.7  mm.). 

Kind  :  Circular-arc  cam. 
Pulsion  :  \  (135.5  mm.)  =  5.33  in.  per  sec. 
Suction  :  f  (  45.2  mm.)  =  1.77  in.  per  sec. 


On  mesh.... 
Size  in  mm.. 

12. 

1.66 

20. 
0.97 

40. 
0.42 

60. 
0.26 

80. 
0.21 

100.  thro' 
0.16 

100. 
0.16 

Total. 

A.        6.1 
B.       65.0 

a      3.9 

.16.3 
60.0 
9.6 

32.4 
45.0 
14.6 

16.9 
35.0 
6.0 

8.7 
40.0 
3.4 

4.0 
45.0 
1.8 

14.2 
50.0 
7.1 

98.6 
46.4 

Percentage  of  sphalerite  in  concentrates  :  46.4. 
Ratio  of  concentration  based  on  original  feed  :  2.32. 

Remarks.  —  The  bedding  and  the  ore-column  pulsated,  and  the  bottom  grains 
of  bedding  much  more  than  in  Test  66. 


TEST  68.  —  Sphalerite  20,  Quartz  80  per 


cent. 


Stroke:  Cam-shaft  rev.  per  min.,  160.     Length,  J  in.  (12.7  mm.). 

Kind  :  Circular-arc  cam. 
Pulsion:  f  (  45.2  mm.)  =  1.77  in.  per  sec. 
Suction:  £  (135.5  mm.)  =  5.33  in.  per  sec. 


On  mesh....!  12. 
Size  in  mm..  11.  66 

20. 
0.97 

40. 
0.42 

60. 
0.26 

80. 
0.21 

100.  thro'  100. 
0.16         0.16 

Total. 

A. 
B. 

a 

1.2 
95.0 
1.1 

8.1 
80.0 
6.4 

36.4 
50.0 
18.2 

21.6 
40.0 
8.6 

11.2 

40.0 
4.4 

5.6 
45.0 
2.5 

16.5 
50.0 

8.2 

100.6 
49.4 

Percentage  of  sphalerite  in  concentrates:  49.4. 
Ratio  of  concentration  based  on  original  feed  :  2.47. 
Remarks. — Movement  of  jig- bed  similar  to  Test  48. 

TEST  69. — Sphalerite  20,  Quartz  80  per  cent. 

Stroke  :  Cam-shaft  rev.  per  min.,  160.     Length,  £  in.  (12.7  mm.). 

Kind  :  Involute  cam. 
Pulsion  :  J  (101.6  mm.)  =  4  in.  per  sec. 
Suction  :  £  (  50.8  mm.)  =  2  in.  per  sec. 


On  mesh....|  12. 
Size  in  mm..  1  1.66 

20. 
0.97 

40. 
0.42 

60. 

0.26 

80. 
0.21 

100.  thro'  100. 
0.16         0.16 

Total. 

A. 
B. 
C. 

5.2 
70.0 
3.5 

18.2 
75.0 
13.5 

32.7 
45.0 
14.8 

17.7 
45.0 
7.9 

9.2 

50.0 
4.6 

4.1 
50.0 
2.0 

12.5 

55.0 
6.8 

99.6 
53.1 

Percentage  of  sphalerite  in  concentrates :  53.1. 

Ratio  of  concentration  based  on  original  feed:  2.65. 

Remarks. — The  entire  jig-bed  moved  en  masse,  and  was  very  mobile.  As  in  all 
cases  of  this  kind,  the  upper  part  of  the  ore-column  had  a  longer  amplitude  of 
vibration  and  required  a  longer  time  in  which  to  complete  it  than  the  grains 
(whether  bedding  or  ore)  nearer  the  bottom. 


INVESTIGATION    ON    JIGGING.  43 

TEST  70. — Sphalerite  20,  Quartz  80  per  cent. 

Stroke:  Cam-shaft  rev.  per  min.,'  160.     Length,  \  in.  (12.7  mm.). 

Kind :  Involute  cam. 
Pulsion  :  %  (  50.8  mm.)  =  2  in.  per  sec. 
Suction  :  £  (101.6  mm.)  =  4  in.  per  sec. 


On  mesh....!  12. 
Size  in  mmjl.66 

20. 
0.97 

40. 
0.42 

60. 
0.26 

80. 
0.21 

100.  thro'  100. 
0.16         0.16 

Total. 

A. 
B. 

a 

1.1 

95.0 
1.0 

8.7 
80.0 
6.8 

40.6 
45.0 
16.2 

20.8 
35.0 

7.4 

10.5 
40.0 
4.2 

4.5 
50.0 
2.2 

13.7 

60.0 
8.1 

99.9 
45.9 

Percentage  of  sphalerite  in  concentrates:  45.9. 
Katio  of  concentration  based  on  original  feed  :  2.29. 
Remarks. — Movement  of  jig-bed  similar  to  Test  50. 


TEST  71.— Sphalerite  20,  Quartz  80  per  cent. 

Stroke  :  Cam-shaft  rev.  per  min.,  160.     Length,  £  in.  (6.35  mm.). 

Kind:  Circular-arc  cam. 
Pulsion  :  \  (67.7  mm.)  =  2.66  in.  per  sec. 
Suction  :  £  (22.5  mm.)  =  0.88  in.  per  sec. 


On  mesh.... 
Size  in  mm.. 

12. 
1.66 

20. 
0.97 

40. 
0.42 

60. 
0.26 

80. 
0.21 

100.  thro'  100. 
0.16          0.16 

Total. 

A.        1.1 
B.      95.0 

c.      i.o 

12.0 
8U.O 
9.6 

38.5 
40.0 
14.9 

22.0 
35.0 

7.7 

10.0 
45.0 
4.7 

4.6 
50.0 
2.3 

11.2 

55.0 
6.0 

99.4 
46.2 

Percentage  of  sphalerite  in  concentrates :  46. 2. 
Ratio  of  concentration  based  on  original  feed  :  2.31. 
Remarks. — Movement  of  jig-bed  similar  to  Test  51. 


TEST  72. — Sphalerite  20,  Quartz  80  per  cent. 

Stroke  :  Cam-shaft  rev.  per  min.,  160.     Length,  \  in.  (6.35  mm.). 

Kind  :  Circular-arc  cam. 
Pulsion  :  f  (22.5  mm.)  =  0.88  in.  per  sec. 
Suction  :  J  (67.7  mm.)  =  2.66  in.  per  sec. 


On  mesh.... 
Size  in  mm.. 

12.           20. 
1.66         0.97 

40. 
0.42 

60. 
0.26 

80. 
0.21 

100.  thro'  100. 
0.16          0.16 

Total. 

A.        1.8          10.6 
B.    10U.O         95.0 
C.        1.8           9.9 

31.2 

70.0 
21.7 

22.2 

50.0 
11.1 

12.4 
45.6 
5.6 

6.4 

50.0 
3.8 

15.2 
60.  0 
9.0 

99.8 
62.9 

Percentage  of  sphalerite  in  concentrates  :  62.9. 
Ratio  of  concentration  based  on  original  feed  :  3.14. 

Remarks. — The  entire  mass  except  the  lower  part  of  the  bedding  pulsated  en 
masse,  and  the  ore-column  seemed  quite  mobile. 


44  INVESTIGATION    ON    JIGGING. 

TEST  73. — Sphalerite  20,  Quartz  80  per  cent. 

Stroke :  Cam-shaft  rev.  per  min.,  160.     Length,  }  in.  (6.35  mm.). 

Kind  :  Involute  cam. 
Pulsion  :  |  (50. 8  mm. )  =  2  in.  per  sec. 
Suction  :  f  (25.4  mm.)  =  1  in.  per  sec. 


On  mesh  
Size  in  mm.. 

12. 

1.66 

20. 

0.97 

40. 

0.42 

60. 
0.26 

80. 
0.21 

100. 
0.16 

thro'  100. 
0.16 

Total. 

A.        1.3 
B.     100.0 
C.         1.3 

8.7 
100.0 
8.7 

27.2 
80.0 
21.6 

20.6 
50.0 
10.3 

14.1 
50.0 
7.0 

7.1 
55.0 
3.8 

20.8 
60.0 
12.6 

99.8 
65.3 

Percentage  of  sphalerite  in  concentrates  :  65. 3. 
Katio  of  concentration  based  on  original  feed  :  3.26. 

Remarks. — The  upper  two-thirds  of  bedding  and  the  entire  ore-column  pulsated. 
Ore-column  mobile. 


TEST  74. — Sphalerite  20,  Quartz  80  per  cent. 

Stroke:  Cam-shaft  rev.  per  min.,  160.     Length,  £  in.  (6.35  mm.). 

Kind :  Involute  cam. 
Pulsion  :  f  (25.4  mm.)  =  1  in.  per  sec. 
Suction  :  J  (50.8  mm.)  =  2  in.  per  sec. 


On  mesh  12. 
Size  in  mm..  1.66 

20. 

0.97 

40. 
0.42 

60. 
0.26 

80. 
0.21 

100.  thro'  100. 
0.16         0.16 

Total. 

A.        0.9 
B.    100.0 

a      0.9 

6.5 
100.0 
6.5 

24.5 
85.0 
20.9 

20.6 
65.0 
13.3 

15.5 
55.0 
8.5 

7.9 
60.0 
4.8 

24.1 
60.0 
14.4 

100.0 
69.3 

Percentage  of  sphalerite  in  concentrates  :  69.3. 

Ratio  of  concentration  based  on  original  feed:  3.46. 

Remarks.— The  upper  third  of  bedding  together  with  the  ore-bed  pulsated  en 
...jisse.  The  lower  two-thirds  of  bedding  was  quite  fixed  in  position.  The  top  of 
ore-column,  as  before,  had  a  longer  amplitude. 

TEST  7 6.— Sphalerite  20,  Quartz  80  per  cent. 

Stroke:  Cam-shaft  rev.  per  min.,  160.     Length,  \  in.  (6.35  mm.) 

Kind  :  Eccentric. 
Pulsion  and  Suction  :  \  (33.9  mm.)  =  1.33  in.  per  sec. 


On  mesh 12.  20. 

Size  in  mm..  1.66          0.97 


A.  0.2  4.2 

B.  90.0          90.0 

C.  0.2  3.8 


40. 
0.42 

60. 
0.26 

80. 
0.21 

100.  thro'  100. 
0.16          0.16 

Total. 

29.1 

75.0 
21.8 

20.2 
65.0 
13.0 

13.8 
55.0 
7.4 

7.1 
60.0 
4.2 

24.8 
60.0 
15.0 

99.4 
65.4 

Percentage  of  sphalerite  in  concentrates  :  65.4. 

Ratio  of  concentration  based  on  original  feed  :  3.27. 

Remarks.— The  upper  third  of  bedding  together  with  the  ore-column  pulsated 
en  masse.  The  lower  two-thirds  of  bedding  scarcely  moved.  The  interstitkl  spaces 
of  the  bedding,  as  with  all  experiments  with  the  short  stroke,  filled  with  mineral. 


INVESTIGATION    ON    JIGGING. 


45 


5.  Discussion  of  Results. 

It  is  evident  that  in  a  machine  so  simple  as  the  jig  there  are 
a  number  of  variables,  and  a  series  of  tests  may  therefore  be 


Eccentric 

Involute 

Circular  Arc, 


0      0.2    0.4    0.6    0.8     1.0    1.2    1.4     1.6      0      0.2    0.4    0.6     0.8    1.0    1.2    1.4    1.6    1.8 
MEAN  DIAMETER  OF  GRAINS,  MM.  MEAN  DIAMETER  OF  GRAINS,  MM. 

FIG.  6.  — CHART  OF  RESULTS  OF  GROUPS  1  AND  2  OF  CLASS  I. 

classified  according  to  some  one  of  them.     For  purposes  of  dis- 
cussion, however,  the  tests  that  have  been  conducted  are  grouped 


r 

^- 

-— 

-9 

Eccentric 
Involute 
Circular  Arc 

IN  CONCENT 

I  g  s  t 

X" 

/* 

<X 

^ 

^ 

r\ 

'X 

x 

X*" 

• 

—5 

X-1 

-^" 

-i  05 

t 

/ 

x 

/ 

^ 

X"* 

•  ' 

"""" 

3" 

-20 
§15 

L 

/ 

/ 

**> 

*-*• 

7_ 

X 

X*' 

II 

// 

/ 

/" 

I/' 

/ 

Group  3 
Galena   10  Per  cent. 
Quartz    90  Per  cent. 

/ 

*/ 

Group  4 
Galena   10  Per  cent. 
Quartz   90  Per  cent. 

PERCEf 

•€> 

/,' 

'/ 

// 

/'"' 

/"' 

0.2    0.4    0.6    0.8    1.0     1.2    1.4    1.6      0      0.2    0.4    0.6    0.8    1.0    1.2    1.4    1.0     1.8 
MEAN  DIAMETER  OF  GRAINS,  MM.  MEAN  DIAMETER  OF  GRAINS,  MM. 

PJG.  7. — CHART  OF  RESULTS  OF  GROUPS  3  AND  4  OF  CLASS  I. 

according  to  the  velocity  of  the  rising  current  of  water,  or  pul- 
sion-currents,  as  measured  by  the  mean  piston-speed.     Figs.  6 


46 


INVESTIGATION    ON    JIGGING. 


F 

Iccentric 
nvolute 
ircular  Arc 

_-l 

—  C 



_— 

—31 

•— 



-31 

—29 

/ 

.  



-ri 

/ 

/* 

26 

/ 

/= 



~S 

/ 

. 

>-" 

L  — 

_... 

—22 

2 

/  X 

^__. 

.=--.- 

-••32 

— 

— 

"80 

r^ 

2--- 

:.--- 

—30 
-24 

— 



'/// 

/* 

---33 

/ 

@ 

/ 

/ 

,x. 

^ 

•""^ 

Hfl 

•/ 

/ 

fit 

* 

It 

2 

//'/ 

1  I/ 

-; 

I 

a 

$ 

/J 

I 

1 

Group  1 
Galena   20  Per  cent. 
Quartz    80  Per  cent. 

Qm 

Group  2 
ena  20  Per  cent, 
rtz    80  Per  cent. 

! 

'' 

0.2    0.4    0.6    0.8    1.0    1.2    1.4    1.6      0      0.2    0.4    0.6    0.8    .1.0    1.2    1.4     1.6    1.8 

MEAN  DIAMETER  OF  GRAINS,  MM.  MEAN  DIAMETER  OF  GRAINS,  MM. 

FIG.  8.— CHART  OF  RESULTS  OF  GROUPS  1  AND  2  OF  CLASS  II. 


^** 

B8 

•"25 

Eccentric 
Involute 
.  Circular  Arc 

£ 

•^^ 

-- 

^-27 

•^ 

/ 

,38 

t*~ 

--* 

^-23 

^ 

s^ 

^ 

^-—' 

--J1 

/ 

•»*** 

••/ 

£ 

«? 

fe 

/,- 

'  '/ 

</ 

« 

'  / 

// 

1 

/ 

1, 

1 

// 

// 

ij 

I 

/ 

_  // 

/I/ 

/ 

L 

Group  8 

Galena    20  Per  cent. 
Quartz    80  Per  cent. 

7 

/ 

Group  4 
Galena    20  Per  cent. 
Quartz    80  Per  cent. 



I 

/ 

| 

0.2    0.4    0.6    0.8    1.0    1.2    1.4    1.6      0     0.2    0.4    0.6   0.8    1.0    1.2    1.4    1.6    1.8 

MEAN  DIAMETER  OF  GRAINS,  MM.  MEAN  DIAMETER  OF  GRAINS,  MM. 

FIG.  9. — CHAKT  OK  RESULTS  OF  GROUPS  3  AND  4  OF  CLASS  II. 


INVESTIGATION    ON    JIGGING. 


47 


to  13,  inclusive,  show  graphically  the  results  given  in  row  C, 
under  each  of  the  experiments,  calculated  for  the  mean  diame- 


Eccentric 
Involute 
Circular  Arc 


Group  1 

-    Sphalerite  10  Per  cent. 
Quartz         90  Per  cent. 


Group  2 

Sphalerite  10  Per  cent. 
Quartz         90  Per  cent. 


0.2    0.4   0.6    0.8    1.0    1.2    1.4    1.6     0      0.2    QA    0.6    0.8    1.0    1.2    1.4    1.6    1.8 
MEAN  DIAMETER  OF  GRAINS,  MM.  MEAN  DIAMETER  OF  GRAINS,  MM. 

FIG.  10.— CHART  OF  RESULTS  OF  GROUPS  1  AXD  2  OF  CLASS  III. 


PERCENTAGE  OF  SPHALERITE  IN  CONCENTRATE 

^oSKggggg&gg 

1 

^4.'> 

TT 

ccentric 
ivolute 
ircular  Arc 

^ 

-^ 

c 

/ 

/S 

/ 

-ZZ- 

% 

/ 

'"•X 

,/>- 

***'-' 

/ 

'''/ 

;•• 

,„--" 

*m  ii  '"* 

"^^ 

/ 

^ 

S 

? 

XT" 

.-  ' 

' 

/ 

/ 

V 

/', 

^ 

// 

Group   3 
Sphalerite    10  Per  cent. 
Quartz          90  Per  cent. 

^ 

Group  4 
Sphalerite    10  Per  cent. 
Quartz         90  Per  cent. 

X 

/ 

/ 

/^ 

1 

/-'^ 

C.2    0.4    0.6    0.8     1.0    1.2    1.4    1.6      0      0.2    0.4    0.6    0.8    1.0    1.2    1.4    1.6    1.8 
MEAN  DIAMETER  OF  GRAINS,  MM.  MEAN  DIAMETER  OF  GRAINS,  MM. 

FIG.  11.— CHART  OF  RESULTS  OF  GRODPS  3  AND  4  OP  CLASS  III. 

ter  of  the  material.    Since  all  material  treated  on  the  jig  passed 
through  a  screen  having  a  square  hole,  the  mean  length  of  the 


48 


INVESTIGATION    ON    JIGGING. 


PERCENTAGE  OF  SPHALERITE  IN  CONCENTRATE 

c*sssisgg&ft£8:8S3 

i 
j 

ccentric 
nvolute 
Circular  Arc 

,.- 

.-— 

To 

c 

-_73 

\ 

^ 

,'— 



—  7i 

X 

'x"" 

,; 

/'' 

is'-' 

.-' 

X 

X 

^ 

—  — 

_  —  •  — 

-66 
—69 

7 

x 

: 

^. 

*^- 



—70 

/ 

x 

,' 

/ 

.- 

-===- 

71 

-=r=r-~- 

,=70 

a  ,- 

-'" 

,---' 

'' 

I 

/ 

x^ 

x- 

—34 

,\ffY, 

/ 

'  I 

^ 

/     x 

**' 

JUT 

/I/4'- 

M. 

Cl 

m 

I 

y 

j  I// 

/ft! 

j 

1 

}'/J                    V    .J 

Group  1 
lalerite    20  Per  cent, 
irtz           80  Per  cent 

/ 
/  J 

H 

Group  2 
Sphalerite    20  Per  cent. 
Quartz          80  Per  cent. 

'£'  1           p 

T  \        Q" 

r 

_J 

r 

1 

0     0.2    0.4    O.G    0.8     1.0    1.2    1.4     1.6      0     0.2    0.4    0.6    0.8    1.0    1.2    1.4     1.6     1.8 
MEAN  DIAMETER  OF  GRAINS,  MM.                     MEAN  DIAMETER  OF  GRAINS,  MM. 

FIG.   12.—  CHART  OF  RESULTS  or  GROUPS  I  AND  2  OK  CLASS  IV. 

/- 

___  ' 

—  -^ 

-«M 

I^r 

centric 
volute 
pcular  Arc 

Xx 

' 

--07 

01 

X 

x 

' 

s~ 

^  — 

-  04 

.—  - 

—  • 

-C,3 

// 

X 

:> 

'' 

/ 

^ 

I 

/  --x 

~ 

X 

^—  * 

p*^* 

-01 

/// 

. 

f 

X 

I 

/ 

/ 

/ 

"^ 

III 

y 

/ 

1 

Group  3 
Sphalerite   20  Per  cent. 
Quartz         80  Per  cent. 

//- 

Group  4 
Sphalerite  20  Per  cent. 
Quartz         80  Per  cent. 



F 

> 

? 

' 

1 

1 

/ 

0.2   0.4    0.6     0.8    1.0    1.2     1.4    1.6     0      0.2    0.4    0.6     0.8    1.0     1.2    1.4    1.6    1.8 
MEAN  DIAMETER  OF  GRAINS, 'MM.  MEAN  DIAMETER  OF  GRAINS,  MM. 

FIG.  13. — CHART  OF  RESULTS  OF  GROUPS  3  AND  4  OF  CLASS  IV. 

sides  of  which  was  equal  to  2.136  mm.,  and  from  that  as  a 
maximum  to  the  very  finest  dust,  it  has  been  assumed  that  the 


INVESTIGATION    ON    JIGGING.  49 

mean  diameter  of  the  grain  caught  on  the  1.66-mm.  screen  is 
(2.136  -f  1.66)  -T-  2  =  1.90  mm. ;  those  passing  the  1.66-mm. 
screen  and  caught  on  the  0.97-mm.  screen,  have  a  mean  diame- 
ter of  (1.66  -|-  0.97)  -T-  2  =  1.31  mm.,  and  so  on  for  all  the 
sizes;  and,  finally,  that  the  material  passing  the  0.16-mm.  screen 
(the  finest  used  in  these  tests)  had  a  mean  diameter  of  0.08  mm. 
In  the  curves  shown  in  Figs.  6  to  13  the  diameter  of  the  grain  has 
been  plotted  along  the  X  axis,  and  the  weight  of  pure  mineral 
(galena  or  sphalerite)  on  each  screen-size,  as  given  in  the  record 
of  the  tests,  laid  off  on  the  Faxis.  The  points  thus  located  have 
been  joined  by  three  classes  of  lines  :  the  solid  lines  in  all  cases 
represent  the  results  obtained  in  the  tests  made  with  the  eccen- 
tric cam ;  the  dotted  lines,  tests  with  the  involute  cam ;  and, 
finally,  the  broken  lines,  tests  with  the  circular-arc  cams. 

The  velocities  of  the  pulsion-  or  rising-currents,  as  measured 
above,  have  been  divided,  on  purely  arbitrary  grounds,  into  four 
groups  :  (1)  velocities  of  pulsion  2  in.  (50.8  mm.)  per  sec.  and 
less ;  (2)  velocities  of  pulsion  from  2  to  4  in.  (50.8  to  101.6  mm.) 
per  sec.  ;  (3)  velocities  of  pulsiou  from  4  to  6  in.  (101.6  to 
152.4  mm.)  per  sec.;  (4)  velocities  of  pulsion  from  6  to  10.66  in. 
(152.4  to  271  mm.)  per  sec.  With  this  arrangement  it  has  so 
happened  that  in  nearly  every  case  the  tests  with  the  involute 
cam  are  plotted  in  two  groups.  The  experiments  with  the  eccen- 
tric and  circular-arc  cams  occur  once  only  in  each  group.  Since 
each  pair  of  minerals  has  been  run  with  10  and  with  20  per  cent, 
of  either  galena  or  blende,  two  classes  are  to  be  distinguished. 
In  all  cases  under  discussion,  Classes  I.  and  III.  will  refer  to 
mixtures  containing  10  per  cent.,  and  Classes  II.  and  IV.  to  mix- 
tures with  20  per  cent,  of  the  heavy  mineral. 

In  order  to  facilitate  reference,  the  following  classification  is 
given  : 

CLASS  I.  Galena  and  Quartz.     Galena  10,  Quartz  90  per  cent. 
Group  1.    Velocities  of  pulsion    from  0  to    2    in.  (0    to 

50.8  mm.)  per  sec. 
Tests  8,  11,  12,  14,  15,  17,  18. 
Group  2.  Velocities  of  pulsion  from  2  to  4  in.  (50.8  to 

101.6  mm.)  per  sec. 
Tests  2,  4,  6,  9,  10,  12,  16. 


50  INVESTIGATION    ON    JIGGING. 

Group  3.  Velocities  of  pulsion  from  4  to  6  in.  (101.6  to 

152.4  mm.)  per  sec. 
Tests  4,  5,  7,  9. 
Group  4.  Velocities  of  pulsion  from  6  to  10.66  in.  (152.4 

to  271  mm.)  per  sec. 
Tests  1,  3. 
CLASS  II.    Galena   and    Quartz.     Galena   20,   Quartz    80    per 

cent. 
Group  1.    Velocities  of   pulsion   from   0    to   2  in.  (0  to 

50.8  mm.)  per  sec. 
Tests  28,  30,  31,  32,  34,  35,  37. 
Group  2.  Velocities  of  pulsion  from  2  to  4  in.  (50.8  to 

101.6  mm.)  per  sec. 
Tests  22,  24,  26,  29,  30,  31,  33. 
Group  3.  Velocities  of  pulsion  from  4  to  6  in.  (101.6  to 

152.4  mm.)  per  sec. 
Tests  24,  25,  27,  29,  38. 
Group  4.  Velocities  of  pulsion  from  6  to  10.66  in.  (152.4 

to  271  mm.)  per  sec. 
Teste  21,  23. 
CLASS  III.   Sphalerite  and  Quartz.     Sphalerite  10,  Quartz  90 

per  cent. 
Group  1.    Velocities    of  pulsion    from    0    to    2  in.  (0  to 

50.8  mm.)  per  sec. 
Tests  48,  50,  52,  53,  54,  55. 
Group  2.  Velocities  of  pulsion  from  2  to  4  in.  (50.8  to 

101.6  mm.)  per  sec. 
Tests  42,  44,  46,  49,  50,  51,  53. 
Group  3.  Velocities  of  pulsion  from  4  to  6  in.  (101.6  to 

152.4  mm.)  per  sec. 
Tests  44,  45,  47,  49. 
Group  4.  Velocities  of  pulsion  from  6  to  10.66  in.  (152.4 

to  271  mm.)  per  sec. 
Tests  41,  43. 
CLASS  IV.    Sphalerite  and  Quartz.     Sphalerite  20,  Quartz  80 

per  cent. 
Group  1.   Velocities  of  pulsion    from    0  to    2    in.  (0  to 

50.8  mm.)  per  sec. 
Tests  68,  70,  72,  73,  74,  75. 


INVESTIGATION    ON    JIGGING.  51 

Group  2.  Velocities  of  pulsion  from  2  to  4  in.  (50.8  to 

101.6  mm.)  per  sec. 
Tests  62,  64,  66,  69,  70,  71,  73. 
Group  3.  Velocities  of  pulsion  from  4  to  6  in.  (101.6  to 

152.4  mm.)  per  sec. 
Tests  64,  65,  67,  69. 
Group  4.  Velocities  of  pulsion  from  6  to  10.66  in.  (152.4 

to  271  mm.)  per  sec. 
Tests  61,  63. 

Class  L,  Group  1.  Galena,  10  per  cent.  The  two  lowest  ratios 
of  concentration  were  obtained  with  two  tests  with  eccentric 
cam,  using  a  short  stroke  and  a  high  frequency  in  Tests  17  and 
18;  and  of  these  two,  Test  18,  with  only  a  -j^-in.  stroke  and 
400  strokes  per  min.,  yields  the  lowest  ratio  of  the  series.  An 
examination  of  the  screen-analysis  shows  a  marked  difference 
between  Tests  18  and  15 ;  the  longer  and  slower  stroke  has 
caused  a  larger  percentage  of  the  finest  size  to  pass  into  the 
hutch ;  but  the  shorter  and  more  rapid  stroke  has  increased 
the  percentage  of  material  between  1.31  and  0.69  mm.  in  the 
concentrate.  In  this  case,  at  least,  piston-speed  does  not  deter- 
mine whether  the  jig-bed  will  be  pulsated,  or  the  proportions  of 
coarse  and  fine  material  carried  into  the  hutch. 

The  highest  ratio  of  concentration  is  clearly  with  the  involute 
cam,  Test  11,  with  a  pulsion -velocity  of  2  in.  (50.8  mm.)  and 
suction-velocity  of  1  in.  (25.4  mm.)  per  sec.  A  good  catch  of 
fine  material  is  made,  and  the  three  largest  sizes  are  of  good 
proportions  as  to  weight  and  mineral-content — the  sudden  drop 
in  value  for  particles  of  0.34  mm.  diameter  should  be  noted. 

Tests  8,  12,  14,  and  15  represent  the  three  types  of  strokes. 
The  weak  pulsion  and  strong  suction  of  Tests  8  and  14  have 
produced  results  very  similar  to  those  of  the  eccentric.  This 
style  of  cam,  therefore,  between  the  limits  of  this  group,  is  not 
more  efficient  than  the  eccentric.  In  none  of  the  experiments 
of  this  group  has  any  material  of  mean  diameter  1.90  mm. 
been  carried  through  the  sieve  and  into  the  hutch.  It  cannot 
be  said  that  strong  suction  is  superior  to  moderate  suction  in 
saving  the  fines. 

Class  L,  Group  2.  The  minimum  ratio  of  concentration  is 
that  with  the  involute  cam,  Test  4  representing  the  highest 


52  INVESTIGATION    ON    JIGGING. 

limit  of  velocity  of  pulsion  for  this  group  and  very  strong  suc- 
tion. The  strong  suction,  however,  has  not  resulted  in  increas- 
ing the  proportion  of  fines,  probably  owing  to  the  fact  that  there 
is  also  a  rather  high  puleion- velocity..  The  conditions  in  this 
test  have  been  favorable  for  the  recovery  of  grains  of  mean 
diameter  of  0.69  mm.  (on  0.42-mm.  screen).  The  highest  ratio 
of  concentration  is  obtained  in  Test  6,  an  eccentric,  with  velocity 
of  pulsion  and  suction  2.66  in.  (67.7  mm.)  per  sec.  Test  10,  an 
involute  cam,  with  slow  pulsion  and  rapid  suction,  gives  results 
similar  to  Test  6.  Test  9  gives  very  good  results,  with  high 
pulsion  and  slow  suction,  just  the  reverse  of  Test  10.  In  this 
latter  case  the  strong  pulsion  is  clearly  an  advantage,  resulting 
in  almost  as  good  a  saving  of  fines,  and  a  much  larger  and 
cleaner  product  on  the  large  sizes.  Test  4,  with  circular-arc 
cam,  and  Test  16,  with  eccentric  cam,  give  results  quite  close. 
Why  Test  4  should  differ  so  materially  from  Test  2  is  not  easy 
to  explain.  Tests  10  and  4  represent  the  velocity-limits  of  the 
group  and  show  marked  differences  in  results ;  and  in  Tests  4 
and  9,  with  the  same  velocity  of  pulsion,  but  different  suction- 
velocity,  the  strong  suction  has  produced  a  much  smaller  per- 
centage of  the  finest  size  and  contains  less  galena,  although  the 
strong  suction  has  been  very  effective  in  drawing  material  having 
a  mean  diameter  of  0.69  mm.  into  the  hutch.  The  eccentric, 
with  short  stroke  and  high  frequency,  Test  16,  gives  a  low  ratio 
of  concentration.  In  all  cases  only  a  small  catch  is  made  with 
sizes  larger  than  about  1  mm.,  and  at  least  from  75  to  95  per 
cent,  of  the  mineral  saved  in  the  hutch  is  of  a  diameter  of 
0.69  mm.  or  less. 

In  this  group  the  same  pulsion-velocity  but  variable  suction- 
velocity  give  different  results ;  the  high  suction-velocity  is  not 
of  any  distinct  advantage  in  increasing  the  catch  of  fines  or 
in  enriching  any  of  the  sizes.  The  eccentric  at  proper  rotative 
and  pulsion-speeds  yields  results  equal  and  in  most  cases  supe- 
rior to  an  accelerated  and  retarded  stroke. 

Class  I.,  Group  3.  In  this  group  of  four  experiments,  Test 
4,  which  was  also  placed  with  group  2  of  this  class,  and  occu- 
pied the  lowest  position,  is  also  the  lowest  in  this  group.  The 
highest  ratio  of  concentration  is  found  in  Test  9,  an  involute 
cam  with  the  same  pulsion-velocity  as  Test  4,  but  only  one- 
fourth  the  suction-velocity.  As  noted  under  group  2,  the 


INVESTIGATION    ON    JIGGING.  53 

strong  suction  has  resulted  in  producing  a  smaller  amount  of 
the  finest  size,  and  in  a  decreased  percentage  of  galena  in  all 
the  sizes.  The  intermediate  positions  are  marked  by  an  eccen- 
tric cam,  Test  5,  and  a  circular-arc  cam,  Test  7,  and  with  the 
same  velocity  of  pulsion..  The  strong  pulsion  and  weak  suction 
has  resulted  in  a  larger  saving  of  the  fine  material  than  in  the 
case  of  the  eccentric,  and  a  somewhat  higher  ratio  of  concen- 
tration. 

It  appears,  therefore,  that  in  this  group  the  involute  cam 
with  strong  pulsion  and  weak  suction  is  the  most  efficient  in 
producing  a  high  concentrate,  and  the  reverse  of  these  condi- 
tions the  least  efficient;  that  the  circular-arc  cam,  Test  7,  with 
strong  pulsion  and  weak  suction,  is  somewhat  more  efficient 
than  the  eccentric;  and  that  the  same  velocities  of  pulsion 
yield  different  results. 

It  will  be  noted,  also,  that  all  the  tests  in  this  group  produced 
some  of  the  coarsest  size,  and  those  of  strong  pulsion  and  weak 
suction  the  largest  amount.  In  comparing  this  group  with 
group  2  of  this  series,  we  find  that  the  maximum  ratio  has  been 
passed,  and  that  velocities  of  pulsion  more  than  4  in.  (101.6 
mm.)  per  sec.,  with  the  size  of  material  jigged,  should  not  be 
exceeded. 

Class  I.,  Group  4.  Only  two  experiments  occur  in  this  group, 
Tests  1  and  3.  Length  of  stroke  in  each  case  1  in.  It  appears 
that  the  circular-arc  cam  with  the  highest  velocity  of  pulsion 
and  least  velocity  of  suction  gives  a  little  higher  ratio  of  con- 
centration, but  that  the  results  are  very  much  the  same.  The 
proper  limit  for  pulsion-velocities  has  long  since  been  exceeded. 
Comparing  Tests  3  and  4  in  the  same  way,  it  is  found  that 
strong  pulsion  and  weak  suction  produced  practically  the  same 
percentages  of  sieve-sizes,  but  with  strong  suction  the  per- 
centage of  heavy  material  is  much  reduced.  Even  with  these 
high  velocities  of  pulsion,  a  strong  suction  is  not  an  advantage, 
in  increasing  either  the  amount  of  fine  material  drawn  into  the 
hutch  or  the  percentage  of  heavy  mineral. 

Class  II.,  Group  1.  Galena,  20  per  cent.  Of  the  seven  tests 
in  the  group,  the  involute  cam,  Test  31,  with  velocity  of  pul- 
sion at  the  maximum  limit  of  the  group,  gives  the  highest  ratio 
of  concentration.  The  same  was  true  under  Class  I.  The  final 
minimum  ratio  is  indicated  by  the  reciprocal  of  Test  31,  with 


54  INVESTIGATION    ON    JIGGING. 

weak  pulsion  and  strong  suction.  "With  material  up  to  0.69 
mm.  in  diameter,  the  eccentric  with  short  and  rapid  stroke 
gives  the  lowest  ratio  in  Test  37,  while  at  the  same  piston- 
speed  at  twice  the  length  of  stroke  and  half  the  number  of  rev. 
per  min.,  the  values  are  very  close  to  the  maximum  in  Test  35. 

The  involute  cam  in  Test  30,  with  weak  pulsion  and  strong 
suction,  produces  similar  results  but  at  different  velocities,  but 
at  the  same  ratio  to  Test  32.  In  this  case  the  strongest  suction 
has  drawn  a  larger  percentage  of  the  fine  stuff  into  the  hutch, 
but  has  not  enriched  it. 

The  two  circular-arc  cams,  Tests  28  and  34,  with  weak  pul- 
sion and  strong  suction,  give  similar  results,  in  which  about  30 
per  cent,  of  the  hutch-product  passes  through  a  100-mesh  (0.16 
mm.)  sieve.  But  again,  in  Test  31,  with  the  involute  cam, 
strong  pulsion  and  weak  suction,  a  larger  percentage  of  tine 
material  is  drawn  into  the  hutch.  The  eccentric  gives  about 
the  same  percentage  of  fines  as  in  Test  31. 

It  may  be  said  for  this  group  that  the  eccentric  at  the  proper 
length  and  rotative  velocity  gives  excellent  results,  and  is 
generally  superior  to  an  accelerated  or  retarded  stroke.  The 
same  pulsion-velocities  give  different  results. 

Class  II.,  Group  2.  The  minimum  ratio  of  concentration  is 
indicated  by  the  circular-arc  cam,  Test  33,  with  strong  pulsion 
and  weak  suction.  The  maximum  is  attained  with  an  involute 
cam,  Test  81,  with  rapid  pulsion  and  weak  suction.  The  in- 
volute cam  has  already  been  considered  under  the  first  group. 
Test  29,  also  an  involute,  under  the  same  conditions,  gives  good 
ratios,  but  the  higher  pulsion-velocity  results  in  a  smaller  sav- 
ing of  the  very  fine  material;  larger  sizes  appear  more  abund- 
antly in  the  hutch,  however.  Tests  24  and  30,  involute  cams 
with  suction  in  excess  of  pulsion,  give  final  results  that  are  very 
close,  but  the  strongest  suction,  Test  24,  yields  relatively  less 
fine  and  more  coarse  material  than  the  weaker  suction. 

It  will  be  noted,  further,  that  with  the  exception  of  Test  31, 
some  stuff  larger  than  1.66  mm.  is  found  in  all  the  products. 
The  circular-arc  cam  with  very  high  velocity  of  suction  has  pro- 
duced a  relatively  high  percentage  of  the  finest  size.  The 
eccentric,  Test  26,  gives  good  average  results — a  large  per- 
centage by  weight  of  the  finest,  and  containing  at  least  an 
average  percentage  of  galena.  With  the  exception  of  Tests  29 


INVESTIGATION    ON   JIGGING.  55 

and  31,  the  five  other  tests  are,  in  general,  much  the  same. 
Both  of  these  tests  have  been  classed  in  other  groups.  Of  the 
three  highest  ratios  of  concentration,  two  have  low  suction- 
velocity  and  the  third  has  equal  pulsion  and  suction. 

Class  II.,  Group  3.  Of  these  five  tests  the  minimum  is  found 
in  Test  24,  repeating  the  conditions  of  Test  4.  It  will  be 
noted,  however,  that  until  the  size  next  the  largest  is  reached, 
the  lowest  ratio  is  indicated  by  the  eccentric,  Test  38,  with  short 
stroke  and  high  rotative  speed.  Test  29,  involute  cam,  strong 
pulsion  and  weak  suction,  and  Test  25,  eccentric,  at  the  same 
piston-speed  as  Test  38,  give  almost  the  same  final  results. 

The  circular-arc  cam,  Test  27,  strong  pulsion  and  weak  suc- 
tion, produces  results  very  similar  to  those  of  Tests  25  and  29. 

In  all  cases  with  these  high  pulsion-velocities,  more  material 
having  a  diameter  of  1.31  and  1.90  mm.,  and  correspondingly 
less  of  the  finer  sizes,  have  been  obtained.  The  advantages  of 
high  suction-velocity  over  those  of  pulsion  are  not  apparent. 

Class  II.,  Group  4.  An  examination  of  the  two  tests  in  this 
group  indicates  at  once  a  close  correspondence.  The  maximum 
limit  for  pulsion-velocity  has  been  passed,  but  it  appears  that 
with  the  richer  feed  these  velocities  vary  between  considerably 
wider  limits  than  with  the  poorer  material. 

In  general,  it  may  be  said  for  all  the  tests,  that  for  each 
condition  under  which  jigging  takes  place,  certain  sizes — 20-  or 
40-mesh  (0.97  or  0.42  mm.) — are  very  rich,  and  then  on  smaller 
sizes  a  very  violent  drop  in  the  percentage  of  galena  takes  place. 
This  will  be  noticed  for  all  tests  on  galena  and  blende  as  well. 
Also,  that  moderate  suction  and  stronger  pulsion  give  better  re- 
sults than  the  reverse.  The  strong  pulsion  usually  results  in  a 
larger  yield  of  the  coarser  sizes  of  higher  percentage  in  mineral, 
and  the  fines  are  saved  almost  equally  as  well.  In  most  cases 
the  eccentric,  at  the  proper  length  of  stroke  and  rotative  speed, 
is  equal  and  usually  superior  to  accelerated  or  retarded  stroke ; 
but  when  the  stroke  becomes  too  short  and  the  rotative  speed 
high,  the  ratio  falls  off.  Observations  on  the  behavior  of  the 
bed  under  these  conditions  showed  that  the  bedding  and  ore- 
column  pulsated,  although  at  the  same  piston-speed  with  the 
longer  stroke  no  movement  in  the  bedding  took  place.  This 
indicates  that,  with  very  sudden  impulses  to  the  ore-column,  the 
water  acts  more  like  a  solid  than  a  liquid,  and  that  mineral- 


56  INVESTIGATION    ON    JIGGING. 

particles  are  not  subject*  to  the  full  force  of  a  rising  current  of 
water,  but  that  the  material  is  sifted  down  through  the  inter- 
stitial spaces  of  the  bedding.  Possibly  another  cause  is  at  work, 
as  noted  in  the  behavior  of  the  bed  during  the  long  strokes. 
Here  the  top  of  the  bed  pulsated  for  a  longer  time,  and  had  a 
longer  amplitude  of  vibration,  and  therefore  the  grains  on  the 
bottom  came  to  rest  sooner  than  those  above,  which  would  tend 
to  limit  the  size  of  the  particles  passing  into  the  hutch;  and 
the  longer  and  slower  the  stroke  above  the  limits  which  will 
move  the  grains,  the  more  pronounced  will  this  differential 
motion  be,  and  with  it  the  increased  perfection  of  the  classifi- 
cation that  must  take  place. 

Class  III.,  Group  1.  Sphalerite,  10  per  cent.  Here  the  lowest 
ratio  is  found  in  Test  50,  with  weak  pulsion  and  strong  suc- 
tion. An  examination  of  the  weights  and  percentages  of 
Tables  IV.  and  V.  shows,  however,  that  only  relatively  small 
amounts  of  the  finest  sizes  are  secured ;  but  material  ot 
0.69  mm.  (on  40-rnesh)  is  recovered  to  an  amount  equal  to 
about  41  per  cent.,  while  material  larger  or  smaller  than  this 
size  is  not  materially  increased.  Test  48,  under  similar  con- 
ditions, gives  similar  results.  Both  of  these  tests  indicate  that 
strong  suction,  within  the  limits  of  this  group,  is  not  advanta- 
geous. Test  54,  with  the  same  ratio  of  pulsion  and  suction,  but 
only  one-half  the  intensity,  gives  a  higher  ratio  ot  concentra- 
tion and  a  slightly  better  recovery  in  the  finest  sizes.  Test  52, 
under  analogous  conditions,  gives  somewhat,  similar  results, 
except  material  on  20-mesh  (1.31  mm.  mean  diameter).  Test 
53,  involute  cam,  with  strong  pulsion  and  weak  suction,  gives 
very  good  results.  Test  55,  eccentric,  gives  the  best  results  of 
all.  In  this  case,  not  only  a  high  percentage  of  the  finest  sizes 
of  fair  mineral-content  was  obtained,  but  the  coarse  sizes  also 
were  well  represented,  containing  a  high  percentage  ot  sphal- 
erite, which  accounts  chiefly  for  the  high  ratio  of  concentration. 

It  may  be  said  for  this  group  that  the  eccentric  easily  yields 
the  best  results ;  that  strong  suction  and  weak  pulsion  give  the 
lowest,  and  weak  suction  and  strong  pulsion  an  improved  ratio 
of  concentration. 

Class  III.,  Group  2.  An  inspection  of  the  tests  in  this  group 
shows  that  the  lowest  ratio  of  concentration  is  indicated  by 
Test  50,  an  involute  cam,  with  strong  suction  and  weak  pul- 


INVESTIGATION    ON    JIGGING.  57 

sion,  already  considered  in  Class  IIL,  Group  1 ;  and  very  near 
it  is  Test  51,  a  circular-arc  cam,  with  strong  pulsion  and  weak 
suction,  resulting  in  the  production  of  very  small  amounts  oi 
the  finest  sizes ;  but  nearly  45  per  cent,  of  material  on  the  40- 
mesh  (0.69  mm.  mean  diameter).  Tests  42,  44,  and  49  give 
results  in  the  final  ratios  that  are  close  together,  but  differing 
in  the  details.  Test  42,  circular-arc  cam,  with  moderate  pulsion 
and  strong  suction,  and  Test  49,  involute  cam,  with  strong  pul- 
sion and  weak  suction,  give  practically  the  same  final  result; 
and  Test  44,  involute  cam,  with  moderate  pulsion  and  strong 
suction,  similar  results. 

The  two  higher  ratios  are  those  of  Test  46,  eccentric,  and  Test 
53,  involute  cam,  with  strong  pulsion,  but  the  lowest  for  the 
group,  and  less  suction.  An  inspection  of  the  records  of  the 
experiments  shows  that,  with  the  relatively  low  pulsion-velocity 
used,  these  two  tests  yielded  relatively  less  of  the  coarsest  sizes, 
but  increased  amounts  of  the  finest  sizes. 

The  superiority  of  the  eccentric  over  the  other  forms  of  stroke 
is  at  once  evident.  In  the  case  of  all  styles  of  stroke,  the  same 
pulsion-velocity  gives  final  results  much  the  same. 

Class  III.,  Group  3.  Of  the  four  tests  grouped  here,  three 
are  almost  identical — namely,  Tests  44,  47,  and  49 ;  and  of 
these  three,  two  have  already  been  considered  in  Class  III., 
Group  2.  Test  47,  circular-arc  cam,  with  strong  pulsion  and 
weak  suction,  and  Test  49,  also  strong  pulsion  and  weak  suc- 
tion, produce  about  the  same  results  as  very  strong  suction  and 
weaker  pulsion,  but  in  which,  however,  the  pulsion-velocity  is 
about  the  same.  This  indicates  that  the  velocity  of  pulsion  is 
the  principal  determining  factor. 

Class  IIL,  Group  4.  The  two  tests  in  this  group  are  very 
closely  related.  It  is  evident  that  the  proper  velocity  of  pul- 
sion has  been  passed.  The  records  of  the  experiments  show 
that,  at  these  high  velocities,  the  coarse  sizes  readily  pass  into 
the  hutch,  but  at  the  same  time  the  percentage  of  mineral  is 
much  decreased,  and  much  of  the  fine  material  is  lost. 

An  examination  of  the  four  groups  indicates  that  in  the 
fourth  the  maximum  velocity  of  pulsion  has  been  exceeded 
for  good  work,  but  in  the  other  three  groups  the  best  velocity 
is  not  so  clearly  indicated.  With  the  three  eccentrics  good 
ratios  have  been  secured  in  each  of  the  groups,  and  this  is 


58  INVESTIGATION    ON    JIGGING. 

also  the  most  efficient  of  the  three  types  of  stroke.  A  high 
pulsion-velocity  is  very  efficient  in  saving  material  that  rests  on 
20-  and  12-mesh  (1.31  and  1.90  mm.  mean  diameter  of  grain), 
but  on  sizes  smaller  than  these  less  so  than  decreased  velocities. 
A  high  suction- velocity  is  not  generally  more  efficient  in  re- 
covering the  finest  sizes  than  a  more  moderate  one. 

Class  IV.,  Group  1.  Sphalerite,  20  per  cent.  A  comparison 
with  the  corresponding  group  of  Class  II.  shows  many  features 
in  common.  The  lowest  ratio  of  concentration  is  found  in 
Test  70,  and  next  to  it  Test  68,  both  weak  pulsion  and  strong 
suction.  Test  72,  the  reciprocal  of  Test  68,  gives  better  results. 
Tests  73  and  74,  reciprocals  of  each  other,  indicate  that  be- 
tween these  velocities  the  involute  cam  is  very  efficient.  Test 
74,  with  strong  suction,  gives  the  highest  ratio  of  the  group. 

Class  IV.,  Group  2.  Some  differences  as  compared  with  the 
corresponding  group  of  Class  I.  are  found  here.  The  minimum 
ratio  of  concentration  is  marked  by  Test  64,  involute  cam,  with 
moderate  pulsion  and  strong  suction.  Tests  62,  70  and  71 — 
62  and  70,  circular-arc  cams  and  involute,  respectively,  with 
weak  pulsion  and  strong  suction,  and  Test  71,  with  strong 
pulsion  and  weak  suction — give  results  that  do  not  differ 
materially,  indicating  once  more  that  even  though  the  suction- 
velocity  differs  widely,  the  final  results  will  not  differ  widely 
if  the  pulsion-velocities  are  close  together.  The  eccentric, 
Test  66,  shows  a  good  ratio.  Test  73,  an  involute  cam,  with 
stronger  pulsion  than  suction,  gives  the  maximum  ratio  for  the 
group. 

Class  IV.,  Group  3.  The  four  tests  in  this  group  give  re- 
sults agreeing  very  closely  with  the  corresponding  group  of 
Class  I.,  and  the  observations  made  under  that  group  apply 
here. 

Class  IV.,  Group  4.  A  glance  shows  at  once  that  this  group 
agrees  exactly  with  the  corresponding  group  under  Class  I. 

An  examination  of  the  four  groups  of  Class  II.  indicates 
that  in  the  tirst,  with  a  pulsion-velocity  not  exceeding  2  in. 
(50.8  mm.)  per  sec.,  the  highest  ratios  are  obtained,  and  that 
at  these  velocities  by  far  the  largest  percentage  of  the  mineral 
recovered  has  a  mean  diameter  of  0.69  mm.  (through  20-mesh.). 
As  the  velocity  is  increased,  more  of  the  coarse  sizes  appear 
and  less  fine  material. 


INVESTIGATION    ON    JIGGING.  59 

For  both  Classes  III.  and  IV.,  with  sphalerite  and  quartz,  it 
appears  that  generally  a  stronger  pulsion-velocity  than  suction 
is  more  efficient  in  producing  a  better  concentrate,  and  effects 
an  equally  good  saving  of  the  fines.  The  eccentric,  between 
wide  velocity-limits,  is  an  efficient  type  of  stroke.  Of  the  two 
types  of  cams,  the  involute  is  generally  the  best.  An  examina- 
tion of  the  tests  will  show  that  certain  types  and  velocities  of 
strokes  are  especially  suited  to  the  recovery  of  particles  of  fixed 
diameters. 

Y.    DISCUSSION    OF  PULSION    AND    SUCTION. 

Since  the  pulsion-  and  suction-velocity,  as  measured  by  the 
piston-speed,  have  been  the  chief  variables  in  this  investiga- 
tion, the  question  naturally  arises :  can  the  exact  role  of  each 
be  definitely  defined  ? 

The  accepted  meaning  of  the  terms  "pulsion"  and  "suction" 
is  doubtless  familiar  to  all.  A  pulsion-current  is  one  acting 
opposite  to  gravity,  and  tending  to  raise  the  grain  off  the  jig- 
sieve;  and  a  suction-current  is  one  acting  in  the  direction  of 
gravity  and  supplementing  it.  In  both  cases,  therefore,  are 
reactions  caused  by  the  movement  of  a  column  of  water  or 
other  liquid  relative  to  some  solid. 

When  the  results  of  a  series  of  tests  are  arranged  according 
to  the  pulsion-velocity  in  the  free  part  of  the  jig-column,  or,  in 
other  words,  the  piston-speed,  even  though  the  suction-velocity 
differed  widely,  the  final  results  are  quite  close  together,  in- 
dicating that  the  reactions  occurring  during  this  cycle  deter- 
mine the  final  result.  With  a  perfect-fitting  piston,  given  the 
areas  of  piston  and  jig-sieve,  length  and  number  of  strokes  per 
unit  of  time,  the  mean  pulsion-velocity  in  the  free  or  unoccu- 
pied section  of  the  jig-column  may  be  accurately  determined ; 
and  similarly  for  the  suction-velocity. 

It  has  been  demonstrated  that  under  the  reaction  of  pulsion 
with  mixed  sizes  of  grains  of  different  specific  gravities  cer- 
tain definite  positions  are  established  according  to  diameters. 
Thus,  in  the  case  of  quartz  and  galena,  the  grain  of  quartz  in 
equilibrium  with  a  particle  of  galena  was  5.8  times  the  diam- 
eter of  the  galena  grain. 

Stated  in  other  words,  the  results  of  the  pulsion-jig  experi- 
ments indicate  that  in  order  to  effect  a  perfect  separation  by 


60  INVESTIGATION    ON    JIGGING. 

pulsion  alone,  the  grains  should  be  sized  between  the  limits  of 
these  ratios,  which  may  be  distinguished  from  those  of  "  free- 
settling  ratios"  by  "interstitial  equilibrium  factors,"  or  "  hin- 
dered-settling  ratios  or  factors."  It  is  important  to  note  that 
they  are  larger  than  those  obtained  by  Rlttinger's  well-known 
formula.  This  formula  states  that  in  the  case  of  a  sphere  the 
uniform  velocity  under  "  free-falling  "  conditions  is  : 
'v  =  5.11  i/d(z— 1.0) 

in  which, 

v  =  Velocity  of  fall  in  meters  per  second. 

d  =  Diameter  of  sphere  in  meters. 

x  =  Specific  gravity  of  sphere. 

1  =  Specific  gravity  of  liquid  (unity  in  case  of  water). 

Thus,  in  the  case  of  quartz  and  galena,  if  for  x  the  specific 
gravities  of  the  two  minerals  are  substituted,  equating  and  solv- 
ing for  the  respective  diameters,  a  ratio  of  about  4  to  1  is  ob- 
tained. It  is  evident  that  the  reactions  occurring  during  pulsion 
have  resulted  in  increasing  materially  the  ratios  possible  under 
"  free-settling  "  conditions.  It  seems  to  me  that  part  of  this 
increase  may  be  accounted  for  according  to  Professor  Munroe's10 
grain  of  maximum  falling-velocity.  He  has  shown  that  in  a  tube 
the  grain  of  maximum  falling-velocity  is  one  having  a  diameter 
0.4  that  of  the  tube.  Under  the  force  of  pulsion  the  interstitial 
channels  are  constantly  undergoing  a  change  in  their  diameters. 
A  small  grain  of  heavy  mineral  surrounded  by  the  larger  grains 
of  lighter  mineral  will  have  frequent  opportunities  for  occupy- 
ing a  channel  about  2.5  times  its  own  diameter.  No  doubt  the 
greater  acceleration  of  the  small  particle  over  that  of  the  large 
one  will  always  aid  the  separation,  as  pointed  out  by  Rittinger. 

It  is  evident  that  the  experimental  interstitial-factors  or  ratios 
obtained  in  the  pulsion-jig  are  much  smaller  than  called  for 
by  Munroe's  theory,11  where,  in  the  case  of  above  minerals,  large 
grains  closely  surrounded  by  smaller  ones,  he  obtains  a  ratio  of 
about  31  to  1  for  equal-falling  grains. 

Whatever  may  be  the  theoretical  diameter-ratios  between 
two  minerals  under  pulsion,  it  is  an  easy  matter,  as  pointed  out 
by  Professor  Richards,12  to  determine  what  it  is  under  practical 
conditions,  and  the  ratios  that  exist  under  these  conditions  on 
a  jig-bed  are  the  ones  that  most  closely  concern  the  mill-man. 

10  Trans.,  xvii.,  645  (1888-9).  u  Trans.,  xvii.,  650  (1888-9). 

12  Trans.,  xxiv.,  484  (1894). 


INVESTIGATION    ON    JIGGING.  61 

As  a  resultant  of  all  the  forces  acting  upon  the  grains  during 
the  pulsion-cycle,  a  certain  definite  and  distinct  separation  takes 
place  according  to  the  diameter-ratios  of  the  two  minerals. 
When  this  point  has  been  reached,  further  separation,  or  an 
increase  in  the  diameter-ratios,  is  not  possible.  In  order  now 
to  remove  the  small  grain  of  heavy  mineral  from  the  large 
grains  of  light  mineral  associated  with  it,  the  application  of  some 
other  reaction  is  necessary.  This  force  is  suction,  or,  perhaps 
more  properly,  the  reactions  that  occur  during  the  suction-cycle. 

Under  the  conditions  that  exist  in  a  jig-bed,  we  are  dealing 
with  a  number  of  columns  of  water  moving  with  some  velocity 
relative  to  the  grain.  The  forces  acting  upon  the  grain  will 
be  those  of  the  water-currents,  of  gravity,  and  of  the  resist- 
ance opposed  by  the  walls  of  the  channel  or  other  grains. 
The  effect  of  the  water-current  alone  upon  the  grains  may  be 
considered  a  purely  non-selective  force.  For  grains  of  the  same 
size  and  shape  a  given  current  will  exert  as  much  effort  upon  a 
particle  of  galena  as  upon  one  of  quartz.  Any  advantage  that  the 
small  heavy  grain  has  over  its  larger  companion,  due  to  accelera- 
tion, will  always  be  a  positive  force.  The  resistance  offered  to 
the  passage  of  the  grain  by  other  surrounding  grains  will  de- 
pend upon  the  relative  diameter  of  the  channel  and  the  grain, 
and  the  length,  shape,  and  inclination  of  the  channel.  If  the 
grains  are  all  the  same  size  and  shape,  then  the  mean  diame- 
ter of  the  channels  will  be  less  than  the  diameter  of  any  of  the 
grains,  and  none  of  them  could  be  carried  through  the  intersti- 
tial spaces.  Take  as  an  extreme  case  a  column  of  shot,  steel 
balls,  or  marbles  of  the  same  diameter,  they  are  all  absolutely 
fixed  as  regards  any  possible  suction-velocity.  The  same  is 
true,  through  to  a  less  extent,  in  rounded  particles  not  all  the 
same  size,  as  well-worn  sand,  gravel,  etc.  Again,  the  possi- 
bility of  the  mass  becoming  packed  is  small.  Of  course,  the 
reason  for  this  is  well  understood,  and  is  owing  to  the  fact  that 
in  these  cases  the  surfaces  of  the  particles  are  curved,  and 
therefore  the  points  in  contact  are  reduced  to  a  minimum. 
Under  any  practical  conditions  existing  in  the  jig-bed,  the  par- 
ticles are  not  all  the  same  shape  or  size,  and  instead  of  being 
bounded  by  curved  surfaces  they  are  angular  and  bounded  by 
planes.  This  results  in  neighboring  grains  having  not  few  but 
many  points  in  contact,  accompanied  always  by  a  more  or  less 


62  INVESTIGATION    ON    JIGGING. 

wedging  action,  and  therefore  jigging  under  excessive  suction- 
velocity  results  in  a  tight  bed.  The  wider  the  size-ratio  the 
greater  the  effect,  and  vice  versa.  The  possibility  of  applying 
suction  depends  upon  the  ability  to  maintain  within  the  jig-bed 
interstitial  channels  somewhat  larger  than  the  maximum  grain 
to  be  saved.  Under  the  conditions  existing  on  a  jig-bed,  the 
effect  of  increasing  the  diameter-ratio  of  bedding  and  feed,  the 
number  of  bedding-grains  in  a  vertical  column,  or  thickness  of 
bed,  and  the  character  of  the  bedding-grains  themselves,  whether 
they  are  rough  and  angular,  cubical,  or  well  worn  and  spherical, 
is  at  once  evident. 

The  increased  catch  secured  on  a  jig-bed  over  that  obtain- 
able by  rising  current  alone,  under  either  free  or  hindered  set- 
tling conditions,  is  due  to  the  reaction  occurring  during  suc- 
tion. In  order  that  suction  may  become  effective,  it  is  necessary 
that  the  reaction  of  pulsion  precede.  During  pulsion  a  selection 
and  arrangement  takes  place ;  and  during  suction  a  destruction 
of  the  conditions  of  equilibrium  set  up  under  pulsion,  by  the 
removal  of  the  small  heavy  grain  through  the  interstitial  chan- 
nels into  the  hutch,  results.  Suction  always  supplements  gravity, 
but  in  a  way  in  which  gravity  cannot  act  efficiently — that  is, 
in  the  movement  of  grains  in  channels  more  or  less  inclined 
or  crooked,  where  a  particle  could  easily  lodge,  although  large 
enough  for  the  grain  to  move  in  if  vertical.  The  current  moving 
with  high  velocity  in  these  spaces  serves  to  move  the  particle. 
Pulsion  may  be  said  to  be  the  master  reaction,  while  suction  is 
its  necessary  complement,  completing  what  has  been  initiated 
by  pulsion.  Suction  is  therefore  necessary  in  jigging  all  unsized 
material.  Excessive  suction  with  sized  material,  under  prac- 
tical conditions,  would  be  disadvantageous.  With  very  close 
sizing  on  coarse  jigs  it  would  not  be  particularly  harmful,  but 
it  would  be  useless.  In  jigging  under  any  conditions,  more  or 
less  suction  will  be  of  advantage,  as  helping  to  save  the  smaller 
particles  of  heavy  mineral  that  otherwise  might  be  carried  ofi 
with  the  tailings. 

VI.  DISCUSSION  OF  ACCELERATION. 

It  has  been  pointed  out  (Tests  16,  17,  18,  37)  that  with  a 
very  short  and  quick  stroke,  but  relatively  low  piston-speed, 
the  ratio  of  concentration  obtained  was  low.  Moreover,  the 


INVESTIGATION    ON    JIGGING.  63 

jig-bed  pulsated  under  the  influence  of  the  short,  rapid  stroke, 
and  did  not  with  the  longer  one  of  less  frequency,  but  having 
the  same  mean  piston-speed  in  inches  or  millimeters  per  sec. 
This  was  a  movement  of  the  grains  en  masse,  the  bottom  pul- 
sating quite  as  much  as  the  top,  and  was  altogether  different 
from  that  gentle,  selective  action  observed  with  proper  speeds 
and  frequencies.  The  jig-bed  moved  as  it  would  if  acted  on 
by  a  solid  piston  from  below.  Thus,  by  giving  many  quick 
sharp  blows  to  the  jig-bed,  the  water-columns  have  not  time  to 
adjust  themselves  to  the  increased  pressures,  except  by  raising 
the  grain  which  happens  to  be  in  the  direction  of  impulse.  In 
addition  to  the  mean  piston-speeds,  as  derived  from  Professor 
Munroe's  formula,13  the  element  of  time  during  which  the  im- 
pulse lasts  should  be  included.  This  solid  or  piston-effect  of  a 
water-column  can,  perhaps,  never  be  entirely  eliminated,  nor 
does  it  seem  desirable  that  it  should  be.  The  results  show 
that  increased  quantities  of  hutch-work  are  produced,  supple- 
menting suction  by  keeping  the  interstitial  channels  cleared. 
Since  the  grains  on  the  bottom  are  the  first  to  feel  the  impulse 
and  be  raised,  it  has  been  shown  that  true  pulsion  is  dimin- 
ished, and  the  important  reactions  dependent  on  it  dimin- 
ished. Sharp,  rapid  strokes,  by  increasing  the  piston-effect, 
promote  sifting,  and  therefore  aid  suction,  but  decrease  the  re- 
action of  pulsion. 

VII.  RESUME  AND  CONCLUSIONS. 

Referring  to  the  13  conclusions  of  Professor  Munroe,  quoted 
in  the  early  part  of  this  paper,  it  may  be  said  that  no  experiments 
have  been  carried  out  with  the  idea  of  duplicating  the  work  cov- 
ered by  the  first  six  of  his  conclusions.  In  the  absence  of  posi- 
tive experimental  data,  it  may  be  considered  quite  out  of  place 
to  enter  into  a  discussion  of  them.  However,  in  the  light  of 
results  of  the  present  investigation,  a  few  observations  concern- 
ing these  first  six  conclusions  may  be  given.  The  careful  record 
of  so  many  tests,  under  the  conditions  observed  by  Professor 
Munroe,  seems  to  cover  the  field  thoroughly. 

Conclusions  1,  2,  and  3  are  undoubtedly  fundamental  propo- 
sitions in  any  system  of  jigging.  To  Professor  Munroe  is  due 
the  credit  of  having  first  clearly  pointed  these  out  and  applying 

1S  Trans.,  xvii.,  647,  648  (1888-9). 


64  INVESTIGATION    ON    JIGGING. 

them  to  jigging.  Following,  as  corollaries,  are  the  formulas 
given  for  the  velocity  of  fall  of  grains  en  masse.  The  formulas 
for  the  falling- velocities  of  grains  en  masse  under  the  assumed 
conditions,  when  applied  to  piston-speed,  have  been  demon- 
strated by  experiments  with  the  pulsiou-jig,  the  Yezin  jig,  and 
the  Harz  jig  yield  satisfactory  results. 

Conclusion  4  has  been  noted  elsewhere.  A  grain  0.4  the 
diameter  of  the  channel  will  have  a  maximum  falling- velocity, 
which  therefore  increases  its  chance  of  being  saved,  and  of 
increasing  the  interstitial  settling-ratio. 

Conclusion  5,  in  the  first  part,  follows,  also,  from  the  first 
three  conclusions,  and  its  application  fully  demonstrated  by  Pro- 
fessor Munroe.  It  seems  to  me  that  there  is  a  reasonable  doubt 
about  accepting  the  second  part  of  this  conclusion.  There  is 
no  doubt  about  this  part  of  it :  "  The  falling-velocity  . 
[of  a  mass  of  grains]  increases  or  diminishes  with  the  distance 
apart  of  the  grains,"  since  this  is  merely  a  re-statement  of  Con- 
clusions 1,  2,  3,  and  5.  When,  however,  the  balance  of  this 
statement  is  examined — that  is,  " .  .  .  the  velocity  of  the 
current  necessary  to  support  or  raise  the  mass  of  grains  increases 
or  diminishes  with  the  distance  apart  of  the  grains,"  I  believe 
we  are  entitled  to  withhold  judgment  until  it  has  been  shown 
what  these  velocities,  under  the  conditions  of  jigging,  actually 
are.  This  statement  is  true  if  we  assume  that  the  velocities 
supporting  or  raising  the  grain  are  equal  to  the  observed  veloci- 
ties in  the  free  or  unobstructed  part  of  the  tube ;  or  in  practice 
the  piston-speed.  But  are  these  the  velocities  acting  upon  the 
grains  ?  Under  the  conditions  obtaining  on  a  jig-bed,  the 
grains  occupy  a  considerable  area,  and  therefore  constrict  the 
passage.  It  is  a  matter  of  actual  observation  that  the  velocity 
in  the  interstitial  spaces  is  much  higher  than  that  of  the  jig- 
piston.  It  is  the  same  principle  of  conducting  a  given  volume 
of  water  through  a  pipe-line  made  up  of,  say,  a  12-in.  and  a  6-in. 
pipe.  In  the  12-in.  pipe  the  column  of  water  will  have  a  mean 
velocity  of  x  feet  per  sec.,  and  in  the  6-in.  section  the  velocity 
has  been  increased  to  4  x.  Thus,  we  must  be  careful  not  to 
confuse  the  falling-velocity  of  grains  en,  masse  with  the  velocity 
of  the  water-column  actually  supporting  them  during  pulsion. 

It  has  been  noted  by  Professor  Munroe  that  spheres  falling 
in  tubes  have  a  maximum  falling-velocity  when  the  diameter 


INVESTIGATION    ON    JIGGING.  65 

of  the  sphere  is  0.4  that  of  the  tube ;  and  spheres  either  smal- 
ler or  larger  than  this  size  fall  with  less  velocity.  If  the  col- 
umn of  water  in  the  tube  has  a  velocity  of  0,  or  is  at  rest,  a 
solid  falling  through  this  water-column  will  displace  a  vol- 
ume of  water  equal  to  its  own  volume  as  often  as  it  trav- 
erses a  distance  equal  to  one  of  its  three  dimensions.  This 
displaced  volume  must  escape  within  the  interstitial  space  of 
tube  and  body  with  some  velocity,  depending  on  the  velocity  of 
the  falling  body  and  the  ratio  of  the  diameters  of  the  falling 
body  and  the  tube.  If  the  falling  body  has  a  diameter  nearly 
equal  to  that  of  the  tube,  the  area  of  the  interstitial  space  is 
small,  and  a  low  falling-velocity  of  the  body  may  correspond  to 
a  high  interstitial  velocity  of  the  water-current.  Thus,  while 
the  velocity  of  fall  decreases  as  the  diameter  of  the  solid 
approaches  that  of  the  tube,  at  the  same  time  the  velocity  of 
the  current  tending  to  support  it  increases.  If  the  body  has  a 
diameter  equal  to  that  of  the  tube,  any  motion  of  the  solid 
would  mean  an  infinite  velocity  to  the  interstitial  current,  and 
the  body  stops.  On  the  other  hand,  as  the  diameter-ratio 
between  the  solid  and  the  tube  increases,  the  area  of  the  inter- 
stitial space  increases,  and  the  volume  of  displaced  water  de- 
creases, and  with  it  the  interstitial  velocity,  and  the  body  would 
tend  to  fall  with  a  high  velocity ;  but  the  force  causing  it  to 
fall,  its  weight,  is  also  smaller,  and  therefore  its  ability  to  over- 
come the  inertia  of  the  liquid,  and  other  resistances,  is  less,  so 
that  its  falling-velocity  is  less.  The  possibility  of  interstitial 
currents  depends  upon  a  solid  of  any  diameter  less  than  the 
tube,  and  having  a  specific  gravity  greater  than  that  of  the 
liquid,  and  which  is  free  to  fall,  or  resists  the  motion  of  a 
column  of  the  liquid  in  which  it  is  immersed. 

It  is  evident  that  if  a  velocity  be  given  to  the  water-column 
in  the  free  part  of  the  tube  equal  to  the  observed  velocity  of  fall 
of  the  body  in  the  stationary  column,  then  the  body  will  be  sup- 
ported or  remain  at  rest.  This  velocity  of  the  water  in  the 
column  is  the  apparent  velocity  necessary  to  support  the  grain, 
and  some  function  of  the  actual  velocities  supporting  it.  In 
jigging,  it  is  not  so  much  the  velocity  of  fall  of  a  mass  of  grains 
that  concerns  us,  as  the  velocity  of  the  current  necessary  to 
raise  or  support  them.  In  jigging,  the  grains  are  not  free  to 
fall,  since  they  are  firmly  supported  on  a  sieve,  but  they  are 


66  INVESTIGATION    ON    JIGGING. 

quite  free  to  move  when  the  interstitial  currents  are  acting 
in  pulsion.  When  the  force  due  to  the  velocity  of  the  rising 
currents  is  greater  than  all  other  forces  holding  the  body 
at  rest,  then  the  body  moves  in  the  direction  of  the  greatest 
forces,  and  continues  its  motion  so  long  as  the  forces  are  unbal- 
anced. Thus,  it  has  been  observed  that  the  particles  will  be 
raised  to  positions  higher  than  at  rest  during  the  action  of  the 
pulsion-current.  The  grains  in  the  bed  are  being  raised  because 
each  one  in  motion  is  seeking  a  position  higher  up  in  the  column 
where  the  distance  between  grains  is  greater,  or,  in  other  words, 
where  the  interstitial  velocity  is  lower. 

Conclusion  6  admits  of  no  doubt. 

Conclusion  7  is  an  axiom  as  regards  the  first  part.  The 
second  part  concerns  the  ratio  of  equal-falling  particles  of 
the  pair  chosen — namely,  quartz  and  galena.  No  ratios  were 
obtained  in  any  of  the  investigations  approaching  those  called 
for  by  this  theory.  Evidently  the  conditions  required  by  the 
theory  were  not  present.  The  conditions  assumed  were  that 
the  fine  grains  should  closely  surround  the  large  grain  of 
quartz.  It  has  been  observed  in  all  experiments  that  the  large 
grains  quickly  settled  on  the  bottom — the  smaller  and  lighter 
above,  whether  of  bedding  or  ore.  This  fact  was  also  pointed 
out  by  Professor  Munroe  in  his  paper  on  his  experiments 
with  mixed  shot.14  There  is  but  one  force  that  can  carry  the 
small,  light  grain  to  the  top.  That  force  resides  in  the  velocity 
of  the  interstitial  currents  acting  during  pulsion.  Certainly,  in 
the  pulsion-jig  experiments,  where  the  unsized  material  was 
thoroughly  mixed,  and  added  practically  dry  in  order  to  avoid 
any  classification  in  falling  through  a  water-column,  and  where 
very  large  percentages  of  the  heavy  mineral  (over  70  per 
cent.)  were  used,  the  above  ratios  should  have  been  secured. 
In  the  case  of  the  above  pair  it  was  found  that  a  particle  of 
galena  and  one  of  quartz  5.8  times  its  diameter  were  in  equi- 
librium. If  the  conditions  called  for  by  the  theory  were  present, 
and  the  results  not  fulfilled,  then  an  examination  of  the  theory 
is  in  order.  But  we  have  observed  above  that  while  the 
material  was  thoroughly  mixed  when  added  to  the  tube,  the 
fine,  light  grains  immediately  separated  from  the  large,  heavy 

14  Trans.,  xvii.,  649  (1888-9). 


INVESTIGATION    ON    JIGGING.  67 

ones  during  the  first  few  strokes  of  pulsion.  From  this  we 
must  conclude  that  the  fine,  light  grains  were  not  in  equi- 
librium with  the  large  neighbors,  and  sought  positions  higher 
up  in  the  column  where  they  were.  When  this  was  found 
they  remained  fixed,  or  were  in  equilibrium.  These  ratios 
have  been  given  elsewhere.  For  quartz  and  galena  the  ratio 
was  5.8  to  1. 

The  conditions  assumed  cannot,  under  any  possible  condi- 
tions, exist  on  the  jig-bed,  and  therefore  the  results  that  would 
follow  cannot  possibly  be  attained  in  practice.  The  conditions 
would  be  fulfilled  if  we  caged  all  the  light  and  heavy  grains, 
and  prevented  any  movement  among  them ;  but  this  is  the 
very  condition  that  we  do  not  want  on  a  jig-bed.  It  is  hardly 
fair  to  assume  that  if  in  one  way  or  other  we  are  able  to  keep 
a  mass  of  mixed  grains  together,  under  conditions  where  the 
small  fellows  cannot  escape,  therefore  the  small  grain  is  fall- 
ing with  the  same  velocity  as  the  large  grain.  It  is  in  equi- 
librium by  force,  not  choice;  and  on  the  jig-bed  we  try,  as  far 
as  possible,  to  encourage  the  grains  to  exercise  the  latter  and 
not  the  former. 

Possibly  if  formulas  had  been  derived  showing  the  velocity 
of  the  interstitial  currents  (the  currents  supporting  or  raising 
the  grain),  and  from  these,  equal-settling  ratios  were  derived, 
the  values  would  be  much  less  than  31  to  1,  and  probably  close 
to  those  obtained  in  the  pulsion-jig. 

Conclusion  8  follows  from  the  conclusions  1,  2,  3  and  the 
first  part  of  5.  I  can  bear  testimony  as  to  the  practical  accu- 
racy of  this,  since  I  have  calculated  many  a  piston-speed 
and  velocity  in  the  free  tube  in  the  pulsion-jig.  With  the 
formulas  given,  it  has  been  shown  that  with  pulsion-jigs, 
Vezin  jigs,  Harz  jigs,  etc.,  the  piston-velocity  so  calculated 
suffices  to  move  the  grains.  Given  the  size  or  diameter,  and 
the  specific  gravity  of  the  minerals  to  be  separated,  the  jig- 
piston  velocity  may  be  calculated  with  almost  a  nicety.  It  has 
been  shown  in  the  experiments  in  piston-velocity  that  a  consid- 
erable variation  is  permissible  in  jigging. 

Conclusion  9,  the  first  part  of  Conclusion  11  and  all  of  13 
are  corollaries  of  the  last  part  of  Conclusion  7.  Since  the  con- 
ditions assumed  for  Conclusion  7  cannot  exist  on  a  jig-bed, 
therefore  no  support  is  left  for  11  and  13,  and  some  other  ex- 


68  INVESTIGATION    ON    JIGGING. 

planation  must  be  given  to  account  for  the  applicability  of  the 
English  system.  This  action  has  been  discussed  under  pulsion 
and  suction. 

Conclusion  10  has  been  abundantly  demonstrated.  It 
might  be  added  that  if  the  theory  were  applicable  little  or  no 
suction  would  be  necessary. 

Conclusion  11.  The  last  part  of  this  conclusion,  concerning 
the  presence  of  more  or  less  coarse  material  in  jigging  very 
fine  material,  agrees  with  practice,  since,  if  not  in  the  feed,  a 
bed  is  used,  which  fulfills  the  conditions.  The  tests  do  not 
cover  cases  in  which  any  large  percentage  of  feed  was  less  than 
0.10  millimeter. 

Conclusion  12  accords  with  all  results  of  practice  and  experi- 
ment, and  is  therefore  another  fundamental  proposition  in 
jigging. 

Finally,  to  Professor  Munroe  must  be  given  the  credit  for 
having  pointed  out  the  fact  that  bodies  fall  with  less  velocity 
in  tubes  than  in  large  bodies  of  wrater,  and  for  having  dem- 
onstrated the  applicability  of  formulas  based  on  this  fact  to  ob- 
tain correct  jig-piston  velocities  under  the  assumed  conditions. 
It  is  to  be  always  understood  throughout  this  paper,  that 
under  records  of  the  experiments,  where  pulsion-velocity  and 
suction-velocity  are  given,  the  value  expressed  in  inches  or  milli- 
meters per  second  is  that  of  the  piston  or  the  water-column 
in  the  free  or  unobstructed  part  of  the  jig  only,  and  clearly  not 
the  actual  pulsion-velocity  acting  upon  the  grains  during  these 
reactions.  One  is  a  function  of  the  other,  but  under  the  very 
conditions  obtaining  on  a  jig  they  cannot  be  equal. 

Comparing  the  results  given  by  Professor  Richards,  a  part 
of  whose  conclusions  are  quoted  earlier  in  this  paper,  it  will  be 
found  that,  so  far  as  the  experiments  may  be  compared,  there  is 
a  very  close  agreement  between  us.  Since  we  both  started  from 
the  same  experimental  basis,  on  which  we  were  agreed,  it  is  but 
natural  that  our  conclusions  should  be  in  close  harmony.  This 
theorem,  which  forms  the  basis  in  every  practice  of  jigging,  is 
all  important,  and  of  course  is  the  establishment  of  the  value 
of  the  resultant  measured  by  the  diameter  of  grains  differing 
in  specific  gravity  obtained  during  pulsion  alone.  This  factor 
represents  all  that  can  possibly  be  expected  from  every  force 
acting  upon  the  grains  of  a  jig-bed  during  the  time  the  pulsion- 


INVESTIGATION    ON    JIGGING.  69 

currents  are  acting,  or  while  the  grains  are  free  to  fall.  To 
Professor  Richards  is  due  the  credit  of  having  demonstrated  the 
value  of  this  resultant  as  measured  by  the  ratios  of  diameters. 
My  own  researches,  carried  out  in  a  different  manner  (see  pul- 
sion-experiments),  have  abundantly  confirmed  the  substantial 
accuracy  of  these  ratios.  When,  therefore,  Professor  Richards 
says:  "The  two  chief  reactions  of  jigging  are  pulsion  and 
suction,"  I  see  no  escape  from  them.  If  we  go  a  little  further 
and  say :  "  The  reactions  occurring  during  pulsion  and  suction 
are  the  only  reactions  of  jigging,"  we  have  included  every  force 
imaginable  that  can  act  upon  the  grains.  As  pointed  out  above, 
the  resultant  of  all  the  forces  acting  upon  the  grains  during 
pulsion  is  given  by  the  interstitial  or  hindered-settling  ratios  as 
determined  by  Richards  and  myself.  The  resultant  of  suction 
cannot  be  separately  determined,  apart  from  that  of  pulsion. 
There  is  no  determinable  resultant  of  suction  as  measured  by 
a  ratio  or  factor. 

Summarizing  some  of  the  principal  points  brought  out  in  this 
investigation,  I  believe  the  following  may  safely  be  accepted : 

(1)  The  pulsion-reaction  is  by  far  the  most  important  one  in 
the  process  of  jigging.     During  this  period,  with  sized  grains 
of  different  specific  gravities,  with  proper  pulsion-velocity,  the 
separation  between  them  will  be  complete.     The  size-limit  is 
indicated  by  the  hindered-settling  ratio.     If  the  minerals  are 
not  sized,  or  above  these  ratios,  the  separation  cannot  be  com- 
plete, but  a  definite  arrangement  will  result.     The  positions  of 
equilibrium  will  be  attained  when  the  above  ratios  of  diameters 
are  attained,  after  which  further  separation  by  pulsion  is  im- 
possible. 

(2)  Suction  due  to  the  movement  of  water-columns  supple- 
ments gravity.    Resisting  the  sum  of  these  two  forces  is  the  re- 
sistance of  the  walls  of  the  tube  through  which  the  grain  must 
pass.     The  reaction,  as  a  whole,  must  therefore  be  a  resultant. 
The  chief  components  are  the  force  of  the  water-columns,  which 
are  purely  non-selective,  but  act  with  equal  intensity  upon  all 
particles  of  the  same  shape  and  size,  regardless  of  their  specific 
gravity  or  weight.     Any  advantage  that  the  small  heavy  grain 
would  have  over  a  large  light  one  would,  of  course,  appear  in 
the  resultant  tending  to  carry  it  to  the  hutch.     The  effect  of 
the  forces  opposing  the  movement  of  the  grain  depends  upon 


70  INVESTIGATION    ON    JIGGING. 

the  character  of  the  grain,  and  the  conduit  through  which  it  is 
supposed  to  pass.  Under  any  condition,  the  diameter  of  the 
grain  cannot  be  greater  than  that  of  the  conduit.  If  the  chan- 
nels are  inclined,  or  crooked  and  zigzag  (the  condition  obtain- 
ing on  a  jig-bed),  the  particles  will  more  easily  lodge  against 
the  sides  of  a  tube  large  enough  to  pass  through  if  the  tube  were 
vertical,  but  under  the  force  ot  gravity  they  remain  at  rest. 
The  rapidly  descending  water-currents  passing  through  these 
channels  easily  carry  the  grains  along.  Thus  suction,  due  only  to 
the  moving  columns  of  water,  constitutes  a  powerful  impelling 
force  to  carry  through  the  interstitial  spaces  those  particles  which 
under  the  force  of  gravity  alone  cannot  move.  Suction  is,  there- 
fore, a  necessary  complement  to  pulsion  in  the  jigging  of  all 
unsized  material,  and  generally  valuable  in  jigging  under  all 
conditions. 

(3)  From  the  observations  under  (2)  it  is  clear  what  effect 
the  bedding  will  have  upon  the  result.     Any  part  of  the  bed- 
ding or  ore-column  remaining  fixed  during  the  pulsion-cycle 
must  be  looked  upon  merely  as  a  mass  of  very  irregular  tubes, 
of  length  somewhat  greater  than  the  thickness  of  such  part, 
owing  to  their  inclination,  since  they  are  mostly  inclined.     To 
that  extent  they  are  only  an  extension  of  the  jig-sieve.     The 
result  of  thickening  or  thinning  the  bed,  or  of  increasing  or 
decreasing  the  size-ratio  between  bedding  and  feed,  is  evident. 
This  assumes,  of  course,  that  the  largest  particle  or  feed  is 
smaller  than  the  sieve-aperture,  and  always  the  bedding-grain 
must  be  larger  than  the  sieve-aperture.     It  is  evident,  too,  that 
the  shape  of  the  bedding-grain  will    have  a  marked  effect. 
Grains  that  are  more  or  less  equi-dimensional,  as  galena,  etc., 
will  form  a  more  open  bed  than  one  of  antimony,  which  breaks 
into  long  pencil-shaped  grains.     Finally,  of  course,  if  the  bed- 
ding is  in  use  long  enough  all  grains  become  worn  and  spher- 
oidal.    Any  part  of  the  bedding  free  to  pulsate  is  to  be  con- 
sidered as  part  of  the  ore-column,  and  is  amenable  to  all  the 
conditions  applying  to  this  reaction. 

(4)  The  effect  of  very  rapid  acceleration,  amounting  to  a 
shock  or  blow  to  the  bottom  of  the  jig-bed,  is  an  important 
factor.     Its  effect  is  to  accelerate  the  work  done  by  suction, 
and  render  a  larger  catch  possible  with  a  low  mean  piston- 
velocity.     The  pulsation  of  the  jig-bed  due  to  this  force  and 


INVESTIGATION    ON    JIGGING.  71 

that  taking  place  under  the  regular  interstitial  velocity  should 
be  distinguished.     One  sifts,  the  other  separates. 

(5)  The  results  of  the  many  experiments,  in  which  the  piston- 
speeds  during  the  pulsion  and  suction  were  not  the  same,  seemed 
to  show  that  only  by  properly  balancing  the  two  are  the  best 
results  attained.     It  has  been  generally  noted  that  the  eccentric, 
giving  equal  mean  velocities,  yields  about  as  good  results  as  any 
of  the  accelerated  strokes.     This  observation  applies  only  for 
the  size-ratio  used  in  the  tests,  and  it  is  not  safe  to  speculate 
what  the  results  would  be  for  other  sizes. 

(6)  While  the  use  of  the  jig  for  the  treatment  of  material 
sized  between  wide  limits  is  possible  and  practicable,  still  the 
advantages  that  are  bound  to  follow  where  a  more  or  less  perfect 
sizing  has  preceded  cannot  be  denied.     It  must  be  observed, 
that  in  the  English  system  itself,  when  the  hutch-prodncts  of  one 
jig  are  treated  on  another  we  are  using  sizing. 

(7)  The  more  general  application  of  the  English  system,  or 
the  use  of  the  jig  in  the  treatment  of  unsized  material  instead 
of  the  hydraulic  classifier,  seems  to  be  clearly  indicated.     This 
has  been  recognized  in  some  quarters,  but  a  wider  use  than  has 
hitherto  been  accorded  it  appears  to  hold  out  favorable  induce- 
ments.     This  seems  to  be  a  field   eminently  suited  for  the 
English  methods  of  jigging — one  that  is  not  and  cannot  be  filled 
by  the  Continental  system. 

(8)  The  arguments  that  have  been  advanced  for  the  adoption 
of  the  English  system  on  the  ground  that  equal-settling  ratios, 
many  times  larger  than  those  obtainable  under  free-settling  con- 
ditions, exist  on  the  jig-bed,  are  not  tenuble.    These  hypotheti- 
cal ratios  cannot  possibly  exist  on  a  jig-bed. 

In  conclusion,  I  must  acknowledge  the  great  help  and  many 
suggestions  derived  from  the  works  of  Professor  Richards  and 
Professor  Munroe;  to  the  latter  personally,  I  owe  cordial  thanks 
for  numerous  timely  suggestions.  I  have  also  had  the  benefit 
of  his  valuable  criticism  in  the  construction  of  the  laboratory- 
iig,  with  which  many  of  the  experiments  were  made. 


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